Vietnam War

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The Vietnam War (1 November 1955^{[A 1]} – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam was supported by the Soviet Union and China, while South Vietnam was supported by the United States and other anti-communist nations. The conflict was the second of the Indochina wars and a proxy war of the Cold War between the Soviet Union and US. The Vietnam War was one of the postcolonial wars of national liberation, a theater in the Cold War, and a civil war, with civil warfare a defining feature from the outset.^[52] Direct US military involvement escalated from 1965 until its withdrawal in 1973. The fighting spilled into the Laotian and Cambodian Civil Wars, which ended with all three countries becoming communist in 1975.

After the defeat of the French Union in the First Indochina War that began in 1946, Vietnam gained independence in the 1954 Geneva Conference but was divided in two at the 17th parallel: the Viet Minh, led by Ho Chi Minh, took control of North Vietnam, while the US assumed financial and military support for South Vietnam, led by Ngo Dinh Diem.^{[A 8]} The North Vietnamese supplied and directed the Viet Cong (VC), a common front of dissidents in the south which intensified a guerrilla war from 1957. In 1958, North Vietnam invaded Laos, establishing the Ho Chi Minh trail to supply the VC. By 1963, the north had covertly sent 40,000 soldiers of its People's Army of Vietnam (PAVN), armed with Soviet and Chinese weapons, to fight in the insurgency in the south. President John F. Kennedy increased US involvement from 900 military advisors in 1960 to 16,000 in 1963 and sent more aid to the Army of the Republic of Vietnam (ARVN), which failed to produce results. In 1963, Diem was killed in a US-backed military coup, which added to the south's instability.

Following the Gulf of Tonkin incident in 1964, the US Congress passed a resolution that gave President Lyndon B. Johnson authority to increase military presence without declaring war. Johnson launched a bombing campaign of the north and sent combat troops, dramatically increasing deployment to 184,000 by 1966, and 536,000 by 1969. US forces relied on air supremacy and overwhelming firepower to conduct search and destroy operations in rural areas. In 1968, North Vietnam launched the Tet Offensive, which was a tactical defeat but convinced many Americans the war could not be won. Johnson's successor, Richard Nixon, began "Vietnamization" from 1969, which saw the conflict fought by an expanded ARVN while US forces withdrew. The 1970 Cambodian coup d'état resulted in a PAVN invasion and US–ARVN counter-invasion, escalating its civil war. US troops had mostly withdrawn from Vietnam by 1972, and the 1973 Paris Peace Accords saw the rest leave. The accords were broken and fighting continued until the 1975 spring offensive and fall of Saigon to the PAVN, marking the war's end. North and South Vietnam were reunified in 1976.

The war exacted an enormous cost: estimates of Vietnamese soldiers and civilians killed range from 970,000 to 3 million. Some 275,000–310,000 Cambodians, 20,000–62,000 Laotians, and 58,220 US service members died.^{[A 7]} Its end would precipitate the Vietnamese boat people and the larger Indochina refugee crisis, which saw millions leave Indochina, of which about 250,000 perished at sea.^[56][57] 20% of South Vietnam's jungle was sprayed with toxic herbicides, which led to significant health problems.^{[58]: 144–145 [59]} The Khmer Rouge carried out the Cambodian genocide, and the Cambodian–Vietnamese War began in 1978. In response, China invaded Vietnam, with border conflicts lasting until 1991. Within the US, the war gave rise to Vietnam syndrome, an aversion to American overseas military involvement,^[60] which, with the Watergate scandal, contributed to the crisis of confidence that affected America throughout the 1970s.^[61]

Various names have been applied and shifted over time, though Vietnam War is the most commonly used in English. It has been called the Second Indochina War since it spread to Laos and Cambodia,^[62] the Vietnam Conflict,^[63][64] and colloquially 'Nam. In Vietnam it is known as Kháng chiến chống Mỹ (lit. 'Resistance War against America').^[65][66] The Government of Vietnam officially refers to it as the Resistance War against America to Save the Nation.^[67]

Vietnam had been under French control as part of French Indochina since the 1880s. Vietnamese independence movements, such as the Vietnamese Nationalist Party, faced suppression despite growing public support for diverse reformist and revolutionary nationalist causes.^[68][69] Nguyen Sinh Cung established the Indochinese Communist Party (ICP) in 1930; the Marxist–Leninist party aimed to overthrow French rule and establish a communist state.^[70]

Fractures between nationalists and communists emerged in the 1920s,^[71] as the two groups differed in their visions for postcolonial Vietnam: republicanism for the revolutionary nationalists,^[72] and proletarian internationalism for the communists.^[73] The communists’ radical push for centralized control led to a prolonged civil conflict marked by the suppression of rival nationalists,^[74] with the ICP largely responsible for initiating systemic Vietnamese-on-Vietnamese violence.^[75]: 515

In 1940, Japan invaded French Indochina, following France's capitulation to Germany. By 1941, Japan had gained full military access across Indochina and established a dual colonial rule that preserved Vichy French administration while facilitating Japanese military operations.^[76] Cung, now known as Ho Chi Minh, returned to establish the anti-Japanese Viet Minh movement.^[70] From 1944, the US Office of Strategic Services (O.S.S.) provided the Viet Minh with weapons and training to fight the occupying Japanese.^[77][78] US President Franklin D. Roosevelt supported Vietnamese resistance, and proposed Vietnam's independence be granted under an international trusteeship after the war.^[79] The Viet Minh secured their advantage by relocating their operations from southern China into Vietnam and leveraging Allied support.^[80]

In March 1945, Japan, losing the war, overthrew the French government in Indochina, established the Empire of Vietnam, and maintained Emperor Bảo Đại as a figurehead.^[81] Nationalist parties expanded their political influence.^[82] Following the surrender of Japan, the Viet Minh launched the August Revolution, overthrowing the Japanese-backed state and seizing weapons from the surrendering Japanese forces. On 2 September, Ho Chi Minh declared the independence of the Democratic Republic of Vietnam (DRV). However, British and French forces arrived in Indochina to oversee the Japanese surrender south of the 16th parallel, while Chinese Nationalist troops did so in the north. On September 23, the British supported a French coup that overthrew the DRV government in Saigon and reinstated French control.^[83][84] American support for the Viet Minh ended, and O.S.S. forces left as the French sought to reassert control.

Beginning in August 1945, the Viet Minh sought to consolidate power by terrorizing and purging rival Vietnamese nationalist groups and Trotskyist activists.^{[85][86][87][88]: 383–441} In 1946, the Franco-Chinese and Ho–Sainteny Agreements facilitated a coexistence between the DRV and French that strengthened the Viet Minh while undermining the nationalists.^[89][90] That summer, the Viet Minh colluded with French forces to eliminate nationalists, targeted for their ardent anti-colonialism.^{[91][85]: 205–207 [92]: 175–177 [93]: 699–700}

With most of the nationalist partisans defeated,^[94][95] and negotiations broken down, tensions between the Viet Minh and French authorities erupted into full-scale war in December 1946,^[96] a conflict which became entwined with the Cold War. Surviving nationalist partisans and politico-religious groups rallied behind the exiled Bảo Đại to reopen negotiations with France in opposition to communist domination.^{[97][92]: 187–188} While the State of Vietnam, under Bảo Đại as Chief of State, aligned with the anticommunist Western Bloc, the French exploited it to extend their colonial presence and to bolster their standing within NATO.^[98] By adhering to Marxist-Leninist principles, Vietnamese communists monopolized power through a series of radical campaigns.^{[99][100][101]}

The anticommunist Truman Doctrine, first announced by president Harry S. Truman in March 1947, pledged United States support to nations resisting "attempted subjugation by armed minorities or by outside pressures".^[102] After communist China and the Soviet Union recognized the Democratic Republic of Vietnam, the US recognized the French-backed State of Vietnam, based in Saigon, as the legitimate government in February 1950.^{[103]: 377–379 [25]: 88} The outbreak of the Korean War in June convinced Washington policymakers that the war in Indochina was another example of communist expansionism, directed by the Soviet Union.^{[25]: 33–35}

Military advisors from China began assisting the Viet Minh in July 1950.^[104]: 14 Chinese weapons, expertise, and laborers transformed the Viet Minh from a guerrilla force into an army.^{[25]: 26 [105]} In September 1950, the US created the Military Assistance Advisory Group (MAAG) to screen French aid requests, advise on strategy, and train Vietnamese soldiers.^[106]: 18 By 1954, the US had spent $1 billion in support of the French effort, shouldering 80% of the war costs.^[25]: 35

During the Battle of Dien Bien Phu in 1954, US carriers sailed to the Gulf of Tonkin and the US conducted reconnaissance flights. France and the US discussed the use of tactical nuclear weapons, though how seriously this was considered, and by whom, is unclear.^{[107][25]: 75} According to then-Vice President Richard Nixon, the Joint Chiefs of Staff drew up plans to use nuclear weapons to support the French.^[107] Nixon, a so-called "hawk", suggested the US might have to "put American boys in".^[8]: 76 President Dwight D. Eisenhower made American participation contingent on British support, but they were opposed.^[8]: 76 Eisenhower, wary of involving the US in an Asian land war, decided against intervention.^{[25]: 75–76} US intelligence estimates remained skeptical of France's chance of success.^[108]

In May 1954, the French garrison at Dien Bien Phu surrendered. This marked the end of French military involvement in Indochina. At the Geneva Conference, they negotiated a ceasefire with the Viet Minh, and independence was granted to Cambodia, Laos, and Vietnam.^[109][110]

At the 1954 Geneva Conference, Vietnam was temporarily partitioned at the 17th parallel. Ho Chi Minh wished to continue war in the south, but was restrained by Chinese allies who convinced him he could win control by electoral means.^{[111][25]: 87–88} Civilians were allowed to move freely between the two states for 300 days. Elections were to be held in 1956 to establish a unified government.^{[25]: 88–90} However, the US, represented at the conference by Secretary of State John Foster Dulles, objected to the resolution; Dulles' objection was supported only by the representative of Bảo Đại.^[78] John Foster's brother, Allen Dulles, who was director of the Central Intelligence Agency, then initiated a psychological warfare campaign which exaggerated anti-Catholic sentiment among the Viet Minh and distributed propaganda attributed to Viet Minh threatening an American attack on Hanoi with atomic bombs.^{[78][112][25]: 96–97} The CIA's efforts played a minimal role, as Catholic migrants were driven primarily by their own convictions and circumstances rather than external psychological operations.^[113]

During 300 days, up to one million northerners, fearing persecution by the communists, moved south,^{[25]: 96 [114]} including at least 500,000 Catholics, approximately 200,000 Buddhists, and tens of thousands from ethnic minority communities.^[115] The exodus was coordinated by a U.S.-funded $93 million relocation program, which involved the French Navy and US Seventh Fleet to ferry refugees.^[116] The refugees gave the later Ngô Đình Diệm regime a strong anti-communist constituency.^[117] Over 100,000 Viet Minh fighters went north for "regroupment", expecting to return south within two years.^[58]: 98 The Viet Minh left roughly 5,000 to 10,000 cadres in the south as a base for insurgency.^[25]: 104 The last French soldiers left South Vietnam in 1956^[25]: 116 and China withdrew from North Vietnam.^[104]: 14

Between 1953-56, the North government instituted agrarian reforms, including "rent reduction" and "land reform", which resulted in political oppression. During land reform, North Vietnamese witnesses suggested a ratio of one execution for every 160 village residents: about 100,000 executions. As the campaign was mainly in the Red River Delta, 50,000 executions became accepted by scholars.^{[118]: 143 [119][120]: 569 [121]} However, documents from Vietnamese and Hungarian archives indicate executions were much lower, though likely greater than 14,000.^[122] In 1956, leaders in Hanoi admitted to "excesses" and restored much of the land to the original owners.^{[25]: 99–100}

The South, meanwhile, constituted the State of Vietnam, with Bảo Đại as Emperor, and Ngô Đình Diệm as prime minister. Neither the US, nor Diệm's State of Vietnam, signed anything at the Geneva Conference. The non-communist Vietnamese delegation objected to any division of Vietnam, but lost when the French accepted the proposal of Viet Minh delegate Phạm Văn Đồng,^[123]: 134 who proposed Vietnam be united by elections under the supervision of "local commissions".^[123]: 119 The US countered with the "American Plan", with the support of South Vietnam and the UK.^[123]: 140 It provided for unification elections under UN supervision, but was rejected by the Soviets.^[123]: 140 The US said, "With respect to the statement made by the representative of the State of Vietnam, the United States reiterates its traditional position that peoples are entitled to determine their own future and that it will not join in any arrangement which would hinder this".^{[123]: 570–571} Eisenhower wrote in 1954:

I have never talked or corresponded with a person knowledgeable in Indochinese affairs who did not agree that had elections been held as of the time of the fighting, possibly 80% of the population would have voted for the Communist Ho Chi Minh as their leader rather than Chief of State Bảo Đại. Indeed, the lack of leadership and drive on the part of Bảo Đại was a factor in the feeling prevalent among Vietnamese that they had nothing to fight for.^[124]

According to the Pentagon Papers, Diệm would have been a more popular candidate than Bảo Đại against Hồ, stating that "It is almost certain that by 1956 the proportion which might have voted for Ho - in a free election against Diem - would have been much smaller than 80%."^[125] In 1957, independent observers from India, Poland, and Canada representing the International Control Commission (ICC) stated that fair elections were impossible, reporting that neither South nor North had honored the armistice agreement.^[126]

From April to June 1955, Diệm eliminated political opposition in the south by launching operations against religious groups: the Cao Đài and Hòa Hảo of Ba Cụt. The campaign attacked the Bình Xuyên organized crime group, which was allied with members of the communist party secret police and had military elements. The group was defeated in April following a battle in Saigon. As broad opposition to his harsh tactics mounted, Diệm sought to blame the communists.^[8]

In a referendum on the future of the State of Vietnam in October 1955, Diệm rigged the poll supervised by his brother Ngô Đình Nhu and was credited with 98%, including 133% in Saigon. His American advisors had recommended a more "modest" winning margin of "60-70%." Diệm, however, viewed the election as a test of authority.^[127] He declared South Vietnam to be an independent state under the name Republic of Vietnam (ROV), with him as president.^[25] Likewise, Ho Chi Minh and other communists won 99% of the vote in North Vietnamese "elections".^{[118]: 193–194, 202–203, 215–217}

The domino theory, which argued that if a country fell to communism, surrounding countries would follow, was first proposed by the Eisenhower administration.^[103]: 19 John F. Kennedy, then a senator, said: "Burma, Thailand, India, Japan, the Philippines and obviously Laos and Cambodia are among those whose security would be threatened if the Red Tide of Communism overflowed into Vietnam."^[128]

A devout Catholic, Diệm was fervently anti-communist, nationalist, and socially conservative. "Diệm represented narrow and extremist nationalism coupled with autocracy and nepotism."^{[103]: 200–201} Most Vietnamese were Buddhist, and alarmed by Diệm's actions, like his dedication of the country to the Virgin Mary.

In 1955,^[129] Diệm launched the "Denounce the Communists" campaign, during which suspected communists and other anti-government elements were imprisoned, tortured, or executed. He instituted the death penalty in 1956 against activity deemed communist.^[51] The North Vietnamese government claimed that, by November 1957, over 65,000 were imprisoned and 2,148 killed.^[130] 40,000 political prisoners were jailed by 1959.^[58]: 89 In October 1956, Diệm launched a land reform program limiting the size of rice farms per owner. 1.8m acres of farm land became available for purchase by landless people. By 1960, the process had stalled because many of Diem's biggest supporters were large landowners.^{[131]: 14–16}

In May 1957, Diệm undertook a 10-day state visit to the US. Eisenhower pledged his continued support, and a parade was held in Diệm's honor. But Secretary of State Dulles privately conceded Diệm had to be backed because they could find no better alternative.^[132]

Between 1954-57, the Diệm government succeeded in preventing large-scale unrest in the countryside. In April 1957, insurgents launched an assassination campaign, referred to as "extermination of traitors".^[133] 17 people were killed in the Châu Đốc massacre at a bar in July.^[51] By early 1959, Diệm had come to regard the violence as an organized campaign and implemented Law 10/59, which made political violence punishable by death.^[134] There had been division among former Viet Minh, whose main goal was to hold elections promised in the Geneva Accords, leading to activities separate from the other communists and anti-GVN (Government of the Republic of Vietnam) activists. Douglas Pike estimated that insurgents carried out 2,000 abductions, and 1,700 assassinations of officials, village chiefs, hospital workers and teachers from 1957 to 1960.^{[25]: 106 [51]} Violence between insurgents and government forces increased from 180 clashes in January 1960, to 545 in September.^[135]

In September 1960, COSVN, North Vietnam's southern headquarters, ordered a coordinated uprising in South Vietnam and a third of the population was soon living in areas of communist control.^{[25]: 106–107} In December, North Vietnam formally created the Viet Cong (VC) with the intent of uniting all anti-GVN insurgents, including non-communists. It was formed in Memot, Cambodia, and directed through COSVN.^{[104]: 55–58} The VC placed "emphasis on the withdrawal of American advisors and influence, on land reform and liberalization of the GVN, on coalition government and the neutralization of Vietnam." Identities of the leaders were often kept secret.^[51]

Support for the VC was driven by resentment of Diem's reversal of Viet Minh land reforms. The Viet Minh had confiscated large private landholdings, reduced rents and debts, and leased communal lands to poorer peasants. Diem brought the landlords back, and people who had been farming land for years had to return it and pay years of back rent. "The divisions within villages reproduced those that had existed against the French: 75% support for the NLF^{[clarification needed]}, 20% trying to remain neutral and 5% firmly pro-government".^[136]: 73

In March 1956, southern communist leader Lê Duẩn presented a plan to revive the insurgency entitled "The Road to the South", to the Politburo in Hanoi. However, as China and the Soviets opposed confrontation, his plan was rejected.^[104]: 58 Despite this, the North Vietnamese leadership approved tentative measures to revive southern insurgency in December.^[50] Communist forces were under a single command structure set up in 1958.^[137] In May 1958, North Vietnamese forces seized the transportation hub at Tchepone in Southern Laos near the demilitarized zone, between North and South Vietnam.^[138]: 24

The North Vietnamese Communist Party approved a "people's war" on the South in January 1959,^{[25]: 119–120} and, in May, Group 559 was established to upgrade the Ho Chi Minh trail, then a six-month mountain trek through Laos. On 28 July, North Vietnamese and Pathet Lao forces invaded Laos, fighting the Royal Lao Army along the border.^[139]: 26 About 500 of the "regroupees" of 1954 were sent south on the trail during its first year of operation.^[140] The first arms delivery was completed in August 1959.^[141] In April 1960, North Vietnam imposed military conscription for men. About 40,000 communist soldiers infiltrated the south between 1961-63.^[104]: 76

In the 1960 U.S. presidential election, John F. Kennedy defeated Richard Nixon. Although Eisenhower warned Kennedy about Laos and Vietnam, Europe and Latin America "loomed larger than Asia on his sights."^[142]

Kennedy remained committed to the Cold War foreign policy inherited from the Truman and Eisenhower administrations. In 1961, the US had 50,000 troops based in South Korea, and Kennedy faced four crisis situations: the failure of the Bay of Pigs Invasion he had approved in April,^[143] settlement negotiations between the pro-Western government of Laos and the Pathet Lao communist movement in May,^[144] construction of the Berlin Wall in August, and the Cuban Missile Crisis in October. Kennedy believed another failure to stop communist expansion would irreparably damage US credibility. He was determined to "draw a line in the sand" and prevent a communist victory in Vietnam. He told The New York Times after the Vienna summit with Khrushchev, "Now we have a problem making our power credible and Vietnam looks like the place."^[145][146]

Kennedy's policy toward South Vietnam assumed Diệm and his forces had to defeat the guerrillas on their own. He was against the deployment of American combat troops and observed "to introduce U.S. forces in large numbers there today, while it might have an initially favorable military impact, would almost certainly lead to adverse political and, in the long run, adverse military consequences."^[147] The quality of the South Vietnamese military, however, remained poor. Poor leadership, corruption, and political promotions weakened the ARVN. The frequency of guerrilla attacks rose as the insurgency gathered steam. While Hanoi's support for the VC played a role, South Vietnamese governmental incompetence was at the core of the crisis.^[103]: 369

A major issue Kennedy raised was whether the Soviet space and missile programs had surpassed those of the US. Although Kennedy stressed long-range missile parity with the Soviets, he was interested in using special forces for counterinsurgency warfare in Third World countries threatened by communist insurgencies. Although they were intended for use behind front lines after a conventional Soviet invasion of Europe, Kennedy believed guerrilla tactics employed by special forces, would be effective in a "brush fire" war in Vietnam.

Kennedy advisors Maxwell Taylor and Walt Rostow recommended US troops be sent to South Vietnam disguised as flood relief workers.^[148] Kennedy rejected the idea but increased military assistance. In April 1962, John Kenneth Galbraith warned Kennedy of the "danger we shall replace the French as a colonial force...and bleed as the French did."^[149] Eisenhower put 900 advisors in Vietnam, and by November 1963, Kennedy had put 16,000.^[25]: 131

The Strategic Hamlet Program was initiated in late 1961. This joint U.S.–South Vietnamese program attempted to resettle the rural population into fortified villages. It was implemented in early 1962 and involved forced relocation and segregation of rural South Vietnamese, into new communities where the peasantry would be isolated from the VC. It was hoped these new communities would provide security for the peasants and strengthen the tie between them and central government. However, by November 1963 the program had waned, and it ended in 1964.^[8]: 1070 In July 1962, 14 nations, including China, South Vietnam, the Soviet Union, North Vietnam, and the US, signed the International Agreement on the Neutrality of Laos.

The inept performance of the ARVN was exemplified by failed actions such as the Battle of Ap Bac in January 1963, in which the VC won a battle against a much larger and better-equipped South Vietnamese force, many of whose officers seemed reluctant to engage.^{[150]: 201–206} The ARVN lost 83 soldiers and 5 US helicopters, serving to ferry troops shot down by VC forces, while the VC lost only 18 soldiers. The ARVN forces were led by Diệm's most trusted general, Huỳnh Văn Cao. Cao was a Catholic, promoted due to religion and fidelity rather than skill, and his main role was to preserve his forces to stave off coups. Washington policymaker concluded Diệm was incapable of defeating the communists and might even make a deal with Ho Chi Minh. He seemed concerned only with fending off coups and had become paranoid after attempts in 1960 and 1962, which he partly attributed to US encouragement. Robert F. Kennedy noted, "Diệm wouldn't make even the slightest concessions. He was difficult to reason with ..."^[151] Historian James Gibson summed up the situation:

Strategic hamlets had failed ... The South Vietnamese regime was incapable of winning the peasantry because of its class base among landlords. Indeed, there was no longer a 'regime' in the sense of a relatively stable political alliance and functioning bureaucracy. Instead, civil government and military operations had virtually ceased. The National Liberation Front had made great progress and was close to declaring provisional revolutionary governments in large areas.^[152]

Discontent with Diệm's policies exploded in May 1963, following the Huế Phật Đản shootings of 9 Buddhists protesting the ban on displaying the Buddhist flag on Vesak. This resulted in mass protests—the Buddhist crisis—against discriminatory policies that gave privileges to Catholics over the Buddhist majority. Ngô Đình Thục, Diệm's elder brother and the Archbishop of Huế, held his anniversary celebrations shortly before Vesak; they were bankrolled by the government, and Catholic flags were prominently displayed. Diệm refused to make concessions to the Buddhists or take responsibility for the deaths. In August 1963, the ARVN Special Forces of Colonel Lê Quang Tung, loyal to Diệm's brother Ngô Đình Nhu, raided pagodas, causing destruction and hundreds of deaths. The Republic of Vietnam sought to harness religious nationalism by promoting spiritual values in opposition to communism's atheism; this approach amplified religious consciousness that challenged the state's authority.^[153]

US officials began discussing regime change during 1963. The United States Department of State wanted to encourage a coup, while the Pentagon favored Diệm. Chief among the proposed changes was removal of Diệm's brother Nhu, who controlled the secret police and special forces, and was seen as being behind Buddhist repression and the Ngô family's rule. This proposal was conveyed to the US embassy in Saigon in Cable 243. The CIA contacted generals planning to remove Diệm, and told them the US would not oppose this, nor punish them by cutting off aid. Diệm was overthrown and executed, along with his brother, on 2 November 1963. When Kennedy was informed, Maxwell Taylor remembered he "rushed from the room with a look of shock and dismay on his face."^[154] Kennedy had not anticipated Diệm's murder. The U.S. ambassador Henry Cabot Lodge, invited coup leaders to the embassy and congratulated them. Lodge informed Kennedy that "the prospects now are for a shorter war".^[155] Kennedy wrote to Lodge congratulating him for "a fine job".^[156]

Following the coup, chaos ensued. Hanoi took advantage and increased its support for the VC. South Vietnam entered political instability, as one military government toppled another. Each new regime was viewed by the communists as a puppet of the Americans; whatever the failings of Diệm, his credentials as a nationalist had been impeccable.^[103]: 328 US advisors were embedded in the South Vietnamese armed forces. They were criticized for ignoring the political nature of the insurgency.^[157] The Kennedy administration sought to refocus US efforts on pacification – which in this case was defined as countering the insurgency^[158][159] – and "winning the hearts and minds" of the population. Military leadership in Washington, however, was hostile to any role for U.S. advisors other than troop training.^[160] General Paul Harkins, the commander of U.S. forces in South Vietnam, confidently predicted victory by Christmas 1963.^[106]: 103 The CIA was less optimistic, warning that "the Viet Cong by and large retain de facto control of much of the countryside and have steadily increased the overall intensity of the effort".^[161]

Paramilitary officers from the CIA's Special Activities Division trained and led Hmong tribesmen in Laos and into Vietnam. The indigenous forces were in the tens of thousands and conducted direct action missions, led by paramilitary officers, against the Communist Pathet Lao forces and their North Vietnamese supporters.^[162] The CIA ran the Phoenix Program and participated in the Military Assistance Command, Vietnam – Studies and Observations Group (MAC-V SOG).^[163]

Kennedy was assassinated on 22 November 1963. Vice President Lyndon B. Johnson had not been heavily involved with policy toward Vietnam;^{[164][A 9]} however he immediately focused on it. On 24 November, he said, "the battle against communism ... must be joined ... with strength and determination."^[166] Johnson knew he had inherited a deteriorating situation,^[167] but adhered to the widely accepted domino argument for defending the South: Should they retreat or appease, either action would imperil other nations.^[168] Findings from RAND's Viet Cong Motivation and Morale Project bolstered his confidence that an air war would weaken the insurgency. Some argue the policy of North Vietnam was not to topple other non-communist governments in South East Asia.^[103]: 48

The military revolutionary council, meeting in lieu of a strong South Vietnamese leader, had 12 members. It was headed by General Dương Văn Minh, whom journalist Stanley Karnow, recalled as "a model of lethargy".^[169] Lodge cabled home about Minh: "Will he be strong enough to get on top of things?" Minh's regime was overthrown in January 1964 by General Nguyễn Khánh.^[170] There was persistent instability in the military: several coups—not all successful—occurred in a short period of time.

On 2 August 1964, USS Maddox, on an intelligence mission along North Vietnam's coast, fired upon and damaged torpedo boats approaching it in the Gulf of Tonkin.^[58]: 124 A second attack was reported two days later on USS Turner Joy and Maddox. The circumstances were murky.^{[25]: 218–219} Johnson commented to Undersecretary of State George Ball that "those sailors out there may have been shooting at flying fish."^[171] An NSA publication declassified in 2005 revealed there was no attack on 4 August.^[172]

The second "attack" led to retaliatory airstrikes, and prompted Congress to approve the Gulf of Tonkin Resolution on 7 August.^[173]: 78 This granted the president power "to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression" and Johnson relied on this as giving him authority to expand the war.^[25]: 221 Johnson pledged he was not "committing American boys to fighting a war that I think ought to be fought by the boys of Asia to help protect their own land".^[25]: 227

The National Security Council recommended an escalation of the bombing of North Vietnam. Following an attack on a U.S. Army base in February 1965,^[174] airstrikes were initiated, while Soviet Premier Alexei Kosygin was on a state visit to North Vietnam. Operation Rolling Thunder and Operation Arc Light expanded aerial bombardment and ground support operations.^[175] The bombing campaign, which lasted three years, was intended to force North Vietnam to cease support for the VC by threatening to destroy North Vietnamese air defenses and infrastructure. It was additionally aimed at bolstering South Vietnamese morale.^[176] Between 1965-68, Rolling Thunder deluged the north with a million tons of missiles, rockets and bombs.^[177]

Bombing was not restricted to North Vietnam. Aerial campaigns targeted different parts of the VC and PAVN infrastructure. These included the Ho Chi Minh Trail through Laos and Cambodia. The ostensibly neutral Laos had become the scene of a civil war, pitting the Laotian government backed by the US, against the Pathet Lao and its North Vietnamese allies.

Aerial bombardment against the Pathet Lao and PAVN forces was undertaken by the US to prevent the collapse of the government, and deny use of the Ho Chi Minh Trail. Between 1964-73, the US dropped two million tons of bombs on Laos, similar to the 2.1 million tons of bombs it dropped on Europe and Asia during World War II, making Laos the most heavily bombed country in history.^[178]

The objective of stopping North Vietnam and the VC was never reached. The Chief of Staff of the United States Air Force Curtis LeMay, however, had long advocated saturation bombing in Vietnam and wrote of the communists that "we're going to bomb them back into the Stone Age".^[25]: 328

Following the Tonkin Resolution, Hanoi anticipated the arrival of US troops and expanded the VC, as well as sending PAVN personnel southwards. They were outfitting the VC forces and standardizing their equipment with AK-47 rifles and other supplies, as well as forming the 9th Division.^{[25]: 223 [179]} "From a strength of approximately 5,000 at the start of 1959 the Viet Cong's ranks grew to about 100,000 at the end of 1964 ... Between 1961-64 the Army's strength rose from about 850,000 to nearly a million men."^[157] US troop numbers deployed were much lower: 2,000 in 1961, rising to 16,500 in 1964.^[180] The use of captured equipment decreased, while more ammunition and supplies were required to maintain regular units. Group 559 was tasked with expanding the Ho Chi Minh Trail, in light of US bombardment. The war had shifted into the final, conventional phase of Hanoi's three-stage protracted warfare model. The VC was tasked with destroying the ARVN, and capturing and holding areas; however, it was not yet strong enough to assault towns and cities.

In December 1964, ARVN forces suffered losses at the Battle of Bình Giã,^[181] in a battle both sides viewed as a watershed. Previously, the VC had utilized hit-and-run guerrilla tactics. At Binh Gia, they defeated a strong ARVN force in a conventional battle and remained in the field for four days.^[182]: 58 Tellingly, South Vietnamese forces were again defeated in June 1965 at the Battle of Đồng Xoài.^[182]: 94

On 8 March 1965, 3,500 U.S. Marines were landed near Da Nang, South Vietnam.^{[25]: 246–247} This marked the beginning of America's ground war. US public opinion overwhelmingly supported the deployment.^[183] The Marines' initial assignment was defense of Da Nang Air Base. The first deployment was increased to nearly 200,000 by December.^{[103]: 349–351} US military had been schooled in offensive warfare. Regardless of policy, US commanders were institutionally and psychologically unsuited to defensive missions.^{[103]: 349–351}

General William Westmoreland informed Admiral U. S. Grant Sharp Jr., commander of US Pacific forces, that the situation was critical,^{[103]: 349–351} "I am convinced that U.S. troops with their energy, mobility, and firepower can successfully take the fight to the NLF (Viet Cong)".^[184] With this recommendation, Westmoreland advocated an aggressive departure from America's defensive posture and sidelining of the South Vietnamese. By ignoring ARVN units, the US commitment became open-ended.^[103]: 353 Westmoreland outlined a three-point plan to win:

• Phase 1. Commitment of US and allied forces necessary to halt the losing trend by the end of 1965.
• Phase 2. US and allied forces mount major offensive actions to seize the initiative to destroy guerrilla and organized enemy forces. This phase would end when the enemy had been worn down and driven back from major populated areas.
• Phase 3. If the enemy persisted, a period of 12–18 months following Phase 2 would be required for final destruction of forces remaining in remote base areas.^[185]

The plan was approved by Johnson and marked a profound departure from the insistence that South Vietnam was responsible for defeating the VC. Westmoreland predicted victory by December 1967.^[186] Johnson did not communicate this change to the media, instead he emphasized continuity.^[187] The change in policy depended on matching the North Vietnamese and VC in a contest of attrition and morale. The opponents were locked in an escalation cycle.^{[103]: 353–354} However Johnson ruled out invasion of North Vietnam due to fears of Chinese or Soviet intervention.^[188] Westmoreland and McNamara touted the body count system for gauging victory, a metric that proved flawed.^[189]

The American buildup transformed the South Vietnamese economy and profoundly effected society. South Vietnam was inundated with manufactured goods. Washington encouraged its SEATO allies to contribute troops; Australia, New Zealand, Thailand and the Philippines^[190] agreed. South Korea asked to join the Many Flags program in return for economic compensation. Major allies, however, notably Canada and the UK, declined troop requests.^[191]

The US and allies mounted complex search and destroy operations. In November 1965, the US engaged in its first major battle with the PAVN, the Battle of Ia Drang.^[192] The operation was the first large scale helicopter air assault by the US, and first to employ Boeing B-52 Stratofortress bombers.^{[25]: 284–285} These tactics continued in 1966–67, however, the PAVN/VC insurgents remained elusive and demonstrated tactical flexibility. By 1967, the war had generated large-scale internal refugees, 2 million in South Vietnam, with 125,000 people evacuated and rendered homeless during Operation Masher alone,^[193] the largest search and destroy operation to that point. Operation Masher had negligible impact however, as the PAVN/VC returned to the province just four months afterwards.^{[194]: 153–156} Despite major operations, which the VC and PAVN would evade, the war was characterized by smaller-unit engagements.^[195] The VC and PAVN would initiate 90% of large firefights, and thus the PAVN/VC would retain strategic initiative despite overwhelming US force and firepower deployment.^[195] The PAVN and Viet Cong had developed strategies capable of countering US doctrines and tactics: see NLF and PAVN battle tactics.

Meanwhile, South Vietnamese politics began to stabilize with the arrival of prime minister Air Marshal Nguyễn Cao Kỳ and figurehead chief of state, General Nguyễn Văn Thiệu, in mid-1965. In 1967, Thieu became president with Ky as his deputy, after rigged elections. Though nominally a civilian government, Kỳ was supposed to maintain real power through a behind-the-scenes military body. However, Thiệu outmanoeuvred and sidelined Kỳ. Thiệu was accused of murdering Kỳ loyalists through contrived military accidents. Thiệu remained president until 1975, having won a one-candidate election in 1971.^[196]

Johnson employed a "policy of minimum candor"^[197] with the media. Military information officers sought to manage coverage by emphasizing stories that portrayed progress. This damaged public trust in official pronouncements. As coverage of the war and the Pentagon diverged, a credibility gap developed.^[197] Despite Johnson and Westmoreland proclaiming victory and Westmoreland stating the "end is coming into view",^[198] internal reports in the Pentagon Papers indicate VC forces retained strategic initiative and controlled their losses. VC attacks against static US positions accounted for 30% of engagements, VC/PAVN ambushes and encirclements for 23%, American ambushes against VC/PAVN forces for 9%, and American forces attacking VC emplacements only 5%.^[195]

In late 1967, the PAVN lured American forces into the hinterlands at Đắk Tô and at the Marine Khe Sanh combat base, where the US fought The Hill Fights. These were part of a diversionary strategy to draw US forces towards the Central Highlands.^[199] Preparations were underway for the Tet Offensive, with the intention of Văn Tiến Dũng forces to launch "direct attacks on the American and puppet nerve centers—Saigon, Huế, Danang, all the cities, towns and main bases ..."^[200] Le Duan sought to placate critics of the stalemate by a decisive victory.^{[201]: 90–94} He reasoned this could be achieved through sparking an uprising in the towns and cities,^[201]: 148 along with defections among ARVN units, who were on leave during the truce period.^[202]

The Tet Offensive began in January 1968, as over 100 cities were attacked by over 85,000 VC/PAVN troops, including assaults on military installations, headquarters, and government buildings, including the US Embassy in Saigon.^{[103]: 363–365} US and South Vietnamese forces were shocked by the scale, intensity and deliberative planning, as infiltration of personnel and weapons into the cities was accomplished covertly;^[200] the offensive constituted an intelligence failure on the scale of Pearl Harbor.^[190] Most cities were recaptured within weeks, except the former imperial capital Huế, which PAVN/VC troops held on for 26 days.^[203] They executed approximately 2,800 unarmed Huế civilians and foreigners they considered spies.^[204][203] In the Battle of Huế American forces employed massive firepower that left 80% of the city in ruins.^{[58]: 308–309} At Quảng Trị City, the ARVN Airborne Division, the 1st Division and a US 1st Cavalry Division regiment held out and overcame an assault intended to capture the city.^{[205][206]: 104} In Saigon, VC/PAVN fighters had captured areas in and around the city, attacking key installations before US and ARVN forces dislodged them.^[25]: 479 Peter Arnett reported an infantry commander saying of the Battle of Bến Tre that "it became necessary to destroy the village in order to save it."^[207][208]

During the first month of Tet, 1,100 American and allied troops, 2,100 ARVN and 14,000 civilians were killed.^[209] After two months, 5,000 ARVN and 4,000 US forces had been killed and 46,000 wounded.^[209] The US claimed 17,000 PAVN/VC had been killed and 15,000 wounded.^{[206]: 104 [205]: 82} A month later the May Offensive was launched; it demonstrated the VC were still capable of orchestrating nationwide offensives.^{[25]: 488–489} Two months later the Phase III offensive was launched. PAVN losses across the offensives was 45,267 killed and 111,179 total casualties.^[210][211] It had become the bloodiest year up to then. The failure to spark a general uprising and lack of defections among the ARVN units meant Hanoi's goals had failed at enormous cost.^{[201]: 148–149}

Prior to Tet, in November 1967, Westmoreland had spearheaded a public relations drive for the Johnson administration to bolster flagging public support.^[212] In a speech to the National Press Club he said "the end comes into view."^[213] Thus, the public was shocked and confused by the Tet Offensive.^[212] Public approval of his performance dropped from 48% to 36%, and endorsement for the war fell from 40% to 26%."^[214] The public turned against Johnson as the offensives contradicted claims of progress.^[212]

During 1968, Westmoreland considered the use of nuclear weapons in a contingency plan codenamed Fracture Jaw, which was abandoned when it became known to the White House.^[215] Westmoreland requested 200,000 additional troops, which was leaked to the media, and the fallout combined with intelligence failures caused him to be removed in March 1968, succeeded by his deputy Creighton Abrams.^[216]

On 10 May 1968, peace talks began between the US and North Vietnam in Paris. Negotiations stagnated for five months, until Johnson halted the bombing of North Vietnam. Hanoi realized it could not achieve a "total victory" and employed a strategy known as "talking while fighting, fighting while talking", in which offensives occurred concurrently with negotiations.^[217]

Johnson declined to run for re-election as his approval rating slumped from 48% to 36%.^[25]: 486 His escalation of the war divided Americans, cost 30,000 American lives by that point and was regarded to have destroyed his presidency.^[25]: 486 Refusal to send more troops was seen as Johnson's admission the war was lost.^[218] As McNamara said, "the dangerous illusion of victory by the United States was therefore dead."^[103]: 367 Vietnam was a major issue during the United States presidential election in 1968. The election was won by Republican Richard Nixon who claimed to have a secret plan to end the war.^{[25]: 515 [219]}

Nixon began troop withdrawals in 1969. His plan to build up the ARVN so it could take over defense of South Vietnam became known as "Vietnamization". As the PAVN/VC recovered from their 1968 losses and avoided contact, Abrams conducted operations aimed at disrupting logistics, with better use of firepower and more cooperation with the ARVN.^[25]: 517 In October 1969, Nixon had ordered B-52s with nuclear weapons to race to the border of Soviet airspace to convince the Soviets, in accordance with the madman theory, he was capable of anything to end the war.^[220][221] Nixon had sought détente with the Soviet Union and rapprochement with China, which decreased tensions and led to nuclear arms reductions. However, the Soviets continued to supply North Vietnam.^[222][223]

On 2 September 1969, Ho Chi Minh died.^[224] The failure of the Tet Offensive to spark an uprising in the south caused a shift in Hanoi's war strategy, and the Giáp-Chinh "Northern-First" faction regained control over military affairs from the Lê Duẩn-Hoàng Văn Thái "Southern-First" faction.^{[225]: 272–274} An unconventional victory was sidelined in favor of conventional through conquest.^{[201]: 196–205} Large-scale offensives were rolled back in favor of small-unit and sapper attacks as well as targeting the pacification and Vietnamization strategy.^[225] Following Tet, the PAVN had transformed from a light-infantry, limited mobility force into high-mobility and mechanized combined arms.^[225]: 189

The anti-war movement was gaining strength in the US. Nixon appealed to the "silent majority" who he said supported the war. But revelations of the 1968 My Lai massacre,^{[25]: 518–521} in which a US Army unit raped and killed civilians, and the 1969 "Green Beret Affair", where Special Forces soldiers, were arrested for the murder^[226] of a suspected double agent,^[227] provoked outrage.

In 1971, the Pentagon Papers were leaked to The New York Times. The secret history of US involvement, commissioned by the Department of Defense, detailed public deceptions by the government. The Supreme Court ruled publication legal.^[228]

Following Tet and decreasing public support, US forces began a period of morale collapse, and disobedience.^{[229]: 349–350 [230]: 166–175} At home, desertion rates quadrupled from 1966 levels.^[231] Among the enlisted, only 2.5% chose infantry in 1969–70.^[231] ROTC enrollment decreased from 191,749 in 1966 to 72,459 by 1971,^[232] and a low of 33,220 in 1974,^[233] depriving the US of much-needed military leadership.

Refusal to engage in patrols or carry out orders emerged, with a case of an entire company refusing orders.^[234] Unit cohesion began to dissipate and focused on minimizing contact with the PAVN/VC.^[230] A practice known as "sand-bagging" started, where units ordered to patrol would go into the country-side, find a site out of view from superiors and radio in false coordinates and reports.^{[194]: 407–411} Drug usage increased, 30% regularly used marijuana,^[194]: 407 while a House subcommittee found 10% used heroin.^{[231][25]: 526} From 1969, search-and-destroy operations became referred to as "search and avoid", falsifying battle reports while avoiding guerrillas.^[235] 900 fragging (killing a fellow office, usually superior) and suspected fragging incidents were investigated, most occurring between 1969-71.^{[236]: 331 [194]: 407} In 1969, field-performance was characterized by low morale and poor leadership.^[236]: 331 The decline in morale was demonstrated by the Battle of FSB Mary Ann in 1971, in which a sapper attack inflicted serious losses on US defenders.^[236]: 357 Westmoreland, no longer in command but tasked with investigation of the failure, cited dereliction of duty, lax defensive postures and lack of officers in charge.^[236]: 357

On the collapse of morale, Shelby Stanton wrote:

In the last years of the Army's retreat, its remaining forces were relegated to static security. The American Army's decline was readily apparent...Racial incidents, drug abuse, combat disobedience, and crime reflected growing idleness, resentment... the fatal handicaps of faulty campaign strategy, incomplete wartime preparation, and the tardy, superficial attempts at Vietnamization. An entire American army was sacrificed on the battlefield of Vietnam.^{[236]: 366–368}

Beginning in 1969, American troops were withdrawn from border areas where most of the fighting took place and redeployed along the coast and interior. US casualties in 1970 were less than half of 1969, after being relegated to less active combat.^[237] While US forces were redeployed, the ARVN took over combat operations, with casualties double US ones in 1969, and triple in 1970.^[238] Post-Tet, membership in the South Vietnamese Regional Forces and Popular Force militias grew, and they could now provide village security, which the Americans had not accomplished.^[238]

In 1970, Nixon announced the withdrawal of an additional 150,000 American troops, reducing US numbers to 265,500.^[237] By 1970, VC forces were no longer southern-majority, nearly 70% were northerners.^[239] Between 1969-71 the VC and some PAVN units had reverted to small unit tactics, instead of nationwide offensives.^[201] In 1971, Australia and New Zealand withdrew their soldiers and US troops were reduced to 196,700, with a deadline to remove another 45,000 troops by February 1972. The US reduced support troops, and in March 1971 the 5th Special Forces Group, the first American unit deployed, withdrew.^{[240]: 240 [A 10]}

Prince Norodom Sihanouk had proclaimed Cambodia neutral since 1955,^[243] but permitted the PAVN/VC to use the port of Sihanoukville and Sihanouk Trail. In March 1969 Nixon launched a secret bombing campaign, called Operation Menu, against communist sanctuaries along the Cambodia/Vietnam border. Only five congressional officials were informed.^{[A 11]}

In March 1970, Sihanouk was deposed by his pro-American prime minister Lon Nol, who demanded North Vietnamese troops leave Cambodia or face military action.^[244] Nol began rounding up Vietnamese civilians in Cambodia and massacring them, provoking reactions from the North and South Vietnamese governments.^[245] In April–May 1970, North Vietnam invaded Cambodia at the request of the Khmer Rouge, following negotiations with deputy leader Nuon Chea. Nguyen Co Thach recalls: "Nuon Chea has asked for help and we have liberated five provinces of Cambodia in ten days."^[246] US and ARVN forces launched the Cambodian campaign in May to attack PAVN/VC bases. A counter-offensive in 1971, as part of Operation Chenla II by the PAVN, recaptured most border areas and decimated Nol's forces.

The US incursion into Cambodia sparked U.S. protests as Nixon had promised to deescalate involvement. Students were killed by National Guardsmen in May 1970 at a Kent State University protest, which provoked further outrage. The administration's reaction was seen as callous, reinvigorating the anti-war movement.^{[230]: 128–129} The US continued to bomb Cambodia as part of Operation Freedom Deal.

Building on the success of ARVN units in Cambodia, and further testing the Vietnamization program, the ARVN was tasked with Operation Lam Son 719 in February 1971, the first major ground operation to attack the Ho Chi Minh Trail. This was the first time the PAVN would field-test its combined arms force.^[201] The first few days were a success, but momentum slowed after fierce resistance. Thiệu had halted the general advance, leaving PAVN armored divisions able to surround them.^[247]

Thieu ordered air assault troops to capture the Tchepone crossroad and withdraw, despite facing four-times larger numbers. During the withdrawal, the PAVN counterattack had forced a panicked rout. Half of the ARVN troops were either captured or killed, half the ARVN/US support helicopters were downed and the operation was a fiasco, demonstrating operational deficiencies within the ARVN.^[248] Nixon and Thieu had sought a showcase victory simply by capturing Tchepone, and it was spun off as an "operational success".^{[249][25]: 576–582}

Vietnamization was again tested by the Easter Offensive of 1972, a conventional PAVN invasion of South Vietnam. The PAVN overran the northern provinces and attacked from Cambodia, threatening to cut the country in half. US troop withdrawals continued, but American airpower responded, beginning Operation Linebacker, and the offensive was halted.^{[25]: 606–637} The US Navy initiated Operation Pocket Money in May, an aerial mining campaign in Haiphong Harbor that prevented North Vietnam's allies from resupplying it with weapons.^[250]

The war was central to the 1972 U.S. presidential election as Nixon's opponent, George McGovern, campaigned on immediate withdrawal. Nixon's Security Advisor, Henry Kissinger, had continued secret negotiations with North Vietnam's Lê Đức Thọ and in October 1972 reached an agreement. Thiệu demanded changes to the peace accord upon its discovery, and when North Vietnam went public with the details, the Nixon administration claimed they were attempting to embarrass the president. The negotiations became deadlocked when Hanoi demanded changes. To show his support for South Vietnam and force Hanoi back to the negotiating table, Nixon ordered Operation Linebacker II, a bombing of Hanoi and Haiphong in December.^{[25]: 649–663} Nixon pressured Thiệu to accept the agreement or face military action.^[251]

On 15 January 1973, all US combat activities were suspended. Lê Đức Thọ and Henry Kissinger, along with the PRG Foreign Minister Nguyễn Thị Bình and a reluctant Thiệu, signed the Paris Peace Accords on 27 January.^{[194]: 508–513} This ended direct U.S. involvement in the war, created a ceasefire between North Vietnam/PRG and South Vietnam, guaranteed the territorial integrity of Vietnam under the Geneva Conference, called for elections or a political settlement between the PRG and South Vietnam, allowed 200,000 communist troops to remain in the south, and agreed to a POW exchange. There was a 60-day period for the withdrawal of US forces. "This article proved ... to be the only one...which was fully carried out."^[252] All US forces personnel were withdrawn by March.^[106]: 260

In the lead-up to the ceasefire on 28 January, both sides attempted to maximize land and population under their control in a campaign known as the War of the flags. Fighting continued after the ceasefire, without US participation, and throughout the year.^{[194]: 508–513} North Vietnam was allowed to continue supplying troops in the South, but only to replace expended material. The Nobel Peace Prize was awarded to Kissinger and Thọ, but Thọ declined saying peace did not yet exist.

On 15 March 1973, Nixon implied the US would intervene militarily if the North launched a full offensive, and Defense Secretary Schlesinger re-affirmed this during his confirmation hearings. Public and congressional reaction was unfavorable, prompting the Senate to pass the Case–Church Amendment to prohibit intervention.^[253]

Northern leaders expected the ceasefire terms would favor their side, but Saigon, bolstered by a surge of US aid just before the ceasefire, began to roll them back. The North responded with a new strategy developed in March 1973, according to Trần Văn Trà.^[254] With US bombings suspended, work on the Ho Chi Minh Trail and other logistical structures could proceed. Logistics would be upgraded until the North was in a position to launch a massive invasion of the South, projected for the 1975–76 dry season. Trà calculated this would be Hanoi's last opportunity to strike, before Saigon's army could be fully trained.^[254] The PAVN resumed offensive operations when the dry season began in 1973, and by January 1974 had recaptured territory lost during the previous dry season.

In South Vietnam, the US departure, and recession after the 1973 oil crisis, hurt an economy dependent on US support and troop presence. After clashes that left 55 ARVN soldiers dead, Thiệu announced in January 1974, that the war had restarted and the Peace Accords were no longer in effect. There were over 25,000 South Vietnamese casualties during the ceasefire period.^{[255][25]: 683} Gerald Ford took over as US president in August 1974, and Congress cut financial aid to South Vietnam from $1 billion a year to $700 million. Congress voted funding restrictions to be phased in through 1975 and total cutoff in 1976.^[25]: 686

The success of the 1973–74 dry season offensive inspired Trà to return to Hanoi in October 1974 and plead for a larger offensive the next dry season. This time, Trà could travel on a drivable highway with fueling stops, a vast change from when the Ho Chi Minh Trail was a dangerous mountain trek.^[256] Giáp, the North Vietnamese defense minister, was reluctant to approve Trà's plan since a large offensive might provoke US reaction and interfere with the big push planned for 1976. Trà appealed to Giáp's superior, Lê Duẩn, who approved it. Trà's plan called for a limited offensive from Cambodia into Phước Long province. The strike was designed to solve logistical problems, gauge the reaction of South Vietnamese forces, and determine whether the US would return.^{[25]: 685–690} On 13 December 1974, PAVN forces attacked Phước Long. Phuoc Binh fell on 6 January 1975. Ford desperately asked Congress for funds to assist and re-supply the South before it was overrun.^[257] Congress refused.^[257] The fall of Phuoc Binh and lack of American response left the South Vietnamese elite demoralized.

The speed of this success led the Politburo to reassess. It decided operations in the Central Highlands would be turned over to General Văn Tiến Dũng and Pleiku should be seized, if possible. Dũng said to Lê Duẩn: "Never have we had military and political conditions so perfect or a strategic advantage as great as we have now."^[258] At the start of 1975, the South Vietnamese had three times as much artillery and twice as many tanks and armored vehicles as the PAVN. However, heightened oil prices meant many assets could not be used. Moreover, the rushed nature of Vietnamization, intended to cover US retreat, resulted in lack of spare parts, ground-crew, and maintenance personnel, which rendered most of it inoperable.^{[229]: 362–366}

On 10 March 1975, Dũng launched Campaign 275, a limited offensive into the Central Highlands, supported by tanks and heavy artillery. The target was Ban Ma Thuột; if the town could be taken, the provincial capital Pleiku and the road to the coast, would be exposed for a campaign in 1976. The ARVN proved incapable of resisting, its forces collapsed. Again, Hanoi was surprised by the speed of its success. Dung urged the Politburo to allow him to seize Pleiku immediately and turn his attention to Kon Tum. He argued that with two months of good weather until the monsoon, it would be irresponsible not to take advantage.^[8]

Thiệu ordered the abandonment of the Central Highlands and less defensible positions in a rushed policy described as "light at the top, heavy at the bottom". While most ARVN forces attempted to flee, isolated units fought desperately. ARVN general Phu abandoned Pleiku and Kon Tum and retreated toward the coast, in the "convoy of tears".^{[25]: 693–694} On 20 March, Thiệu reversed himself and ordered Huế, Vietnam's third-largest city, held at all costs, and then changed policy several times. As the PAVN attacked, panic set in, and ARVN resistance withered. On 22 March, the PAVN attacked Huế. Civilians flooded the airport and docks hoping to escape. As resistance in Huế collapsed, PAVN rockets rained down on Da Nang and its airport. By 28 March 35,000 PAVN troops were poised to attack the suburbs. By 30 March 100,000 leaderless ARVN troops surrendered as the PAVN marched through Da Nang. With the fall of the city, the defense of the Central Highlands and Northern provinces ended.^{[25]: 699–700}

With the north half of the country under their control, the Politburo ordered Dũng to launch the final offensive. The operational plan for the Ho Chi Minh Campaign called for Saigon's capture before 1 May. Hanoi wished to avoid the monsoon and prevent redeployment of ARVN forces defending the capital. PAVN forces, their morale boosted by recent victories, rolled on, taking Nha Trang, Cam Ranh and Da Lat.^{[25]: 702–704}

On 7 April, three PAVN divisions attacked Xuân Lộc, 40 miles (64 km) northeast of Saigon. Fighting raged as the ARVN defenders made a last stand to block PAVN advance. On 21 April however, the exhausted garrison was ordered to withdraw towards Saigon.^{[25]: 704–707} An embittered and tearful Thiệu resigned, declaring that the US had betrayed South Vietnam. He suggested Kissinger had tricked him into signing the Paris Accords, promising military aid that failed to materialize. Having transferred power to Trần Văn Hương on 21 April, he left for Taiwan.^[25]: 714 After having appealed unsuccessfully to Congress for $722 million in emergency aid for South Vietnam, Ford gave a televised speech on 23 April, declaring an end to the war and US aid.^[259][260]

By the end of April, the ARVN had collapsed except in the Mekong Delta. Refugees streamed southward, ahead of the PAVN onslaught. By 27 April, 100,000 PAVN troops encircled Saigon. The city was defended by about 30,000 ARVN troops. To hasten a collapse and foment panic, the PAVN shelled Tan Son Nhut Airport and forced its closure. Large numbers of civilians had no way out.^[25]: 716

Chaos and panic broke out as South Vietnamese officials and civilians scrambled to leave. Martial law was declared. American helicopters began evacuating South Vietnamese, US and foreign nationals from Tan Son Nhut and the embassy compound. Operation Frequent Wind had been delayed until the last possible moment, because of Ambassador Graham Martin's belief Saigon could be held and a political settlement reached. Frequent Wind was the largest helicopter evacuation in history. It began on 29 April, in an atmosphere of desperation, as hysterical crowds of Vietnamese vied for limited space. Frequent Wind continued round the clock, as PAVN tanks breached defenses near Saigon. In the morning of 30 April, the last US Marines evacuated the embassy by helicopter, as civilians swamped the perimeter and poured into the grounds.^{[25]: 718–720}

PAVN troops entered Saigon and overcame all resistance, capturing key buildings and installations.^[261] Tanks from the 2nd Corps crashed through the gates of the Independence Palace and the VC flag was raised above it.^[262] President Dương Văn Minh, who had succeeded Huong two days earlier, surrendered to Lieutenant colonel Bùi Văn Tùng, political commissar of the 203rd Tank Brigade.^{[263][264][265]: 95–96} Minh was escorted to Radio Saigon to announce the surrender.^[266]: 85 The statement was on air at 2:30 pm.^[265]

During the war a large segment of Americans became opposed to US involvement. In January 1967, 32% of Americans thought the US had made a mistake in sending troops.^[267] Opinion steadily turned following 1967 and by 1970 60% believed the US had made a mistake.^[268][269]

Early opposition drew its inspiration from the Geneva Conference. American support of Diệm in refusing elections was seen as thwarting the democracy America claimed to support. Kennedy, while senator, opposed involvement.^[180] Many young people protested because they were being drafted, others because the anti-war movement grew popular among the counterculture. Some within the peace movement advocated unilateral withdrawal. Opposition to the war tended to unite groups opposed to US anti-communism and imperialism,^[270] and for those involved with the New Left. Others, such as Stephen Spiro, opposed the war based on the theory of Just War. Some wanted to show solidarity with the Vietnamese, such as Norman Morrison emulating Thích Quảng Đức.

High-profile opposition increasingly turned to mass protests to shift opinion. Riots broke out at the 1968 Democratic National Convention.^[25]: 514 After reports of American military abuses brought attention and support to the anti-war movement, some veterans joined Vietnam Veterans Against the War. In October 1969, the Vietnam Moratorium attracted millions.^[271] The fatal shooting of students at Kent State University in 1970 led to nationwide university protests.^[272] Anti-war protests declined after the Paris Peace Accords and the end of the draft in 1973, and the withdrawal of troops.

China provided significant support for North Vietnam when the US started to intervene, including finance and hundreds of thousands of military support personnel. China said its military and economic aid to North Vietnam totaled $160 billion (adjusted for 2022 prices);^[7] included were 5 million tons of food (equivalent to a year's production), accounting for 10–15% of the North's food supply by the 1970s.^[7]

In summer 1962, Mao Zedong agreed to supply Hanoi with 90,000 rifles and guns free of charge, and starting in 1965, China began sending anti-aircraft units and engineering battalions, to repair damage caused by American bombing. They helped man anti-aircraft batteries, rebuild roads and railroads, transport supplies, and perform other engineering works. This freed PAVN units for combat. China sent 320,000 troops and annual arms shipments worth $180 million.^[273]: 135 China claims to have caused 38% of American air losses.^[7] China began financing the Khmer Rouge as a counterweight to North Vietnam. China "armed and trained" the Khmer Rouge during the civil war, and continued to aid them afterward.^[274]

The Soviet Union supplied North Vietnam with medical supplies, arms, tanks, planes, helicopters, artillery, anti-aircraft missiles and other military equipment. Soviet crews fired Soviet-made surface-to-air missiles at US aircraft in 1965.^[275] Following the dissolution of the Soviet Union in 1991, Russia acknowledged that the USSR had stationed up to 3,000 troops in Vietnam.^[276] 16 Soviet military personnel were killed in action during the war.^[277]

Between 1953-91, the hardware donated by the Soviet Union included: 2,000 tanks; 1,700 APCs; 7,000 artillery guns; over 5,000 anti-aircraft guns; 158 surface-to-air missile launchers; and 120 helicopters. The Soviets sent North Vietnam annual arms shipments worth $450 million.^{[278][25]: 364–371} From 1965 to 1974, fighting in Vietnam was observed by 11,000 military personnel of the Soviet Armed Forces.^[279] The KGB helped develop the signals intelligence capabilities of the North Vietnamese.^[280]

As South Vietnam was formally part of a military alliance with the US, Australia, New Zealand, France, the UK, Pakistan, Thailand and the Philippines, the alliance was invoked during the war. The UK, France and Pakistan declined to participate, and South Korea, Taiwan, and Spain were non-treaty participants.

The ethnic minorities of South Vietnam, like the Montagnards in the Central Highlands, the Hindu and Muslim Cham, and the Buddhist Khmer Krom, were actively recruited in the war. There was a strategy of recruitment and favorable treatment of Montagnard tribes by the VC, as they were pivotal for control of infiltration routes.^[281] Some groups split off and formed the United Front for the Liberation of Oppressed Races (FULRO) to fight for autonomy or independence. FULRO fought against the South Vietnamese and VC, later fighting against the unified Socialist Republic of Vietnam, after the fall of South Vietnam.^{[citation needed]}

South Vietnam president Diem began a program to settle ethnic Vietnamese Kinh on Montagnard lands in the Central Highlands region. This provoked a backlash from the Montagnards, with some joining the VC. The Cambodians under pro-China Sihanouk and pro-American Lon Nol, supported their fellow Khmer Krom in South Vietnam, following an anti-ethnic Vietnamese policy. Following Vietnamization, many Montagnard groups and fighters were incorporated into the Vietnamese Rangers as border sentries.^{[citation needed]}

War crimes took place, by both sides, including: rape, massacres of civilians, bombings of civilian targets, terrorism, torture, and murder of prisoners of war. Common crimes included theft, arson, and the destruction of property not warranted by military necessity.^[282]

In 1966, the Russell Tribunal was organized by public figures opposed to the war led by Bertrand Russell, to apply the precepts of international law. The tribunal found the US and allies guilty of acts of aggression, use of weapons forbidden by the laws of war, bombardment of targets of a purely civilian character, mistreatment of prisoners, and genocide. Though the tribunal's lack of juridical authority meant findings were ignored by the US and other governments, the hearings contributed to growing evidence which established the factual basis for a counter-narrative to US justifications for the war and inspired hearings, tribunals and legal investigations.^[283]

In 1968, the Vietnam War Crimes Working Group (VWCWG) was established by the Pentagon task force set up in the wake of the My Lai massacre, to ascertain the veracity of claims of US war crimes. Of the crimes reported to military authorities, sworn statements by witnesses and status reports indicated 320 incidents had a factual basis.^[284] The substantiated cases included seven massacres between 1967-71 in which at least 137 civilians were killed; 78 further attacks targeting non-combatants resulting in at 57 deaths and 15 sexually assaulted; and 141 cases of US soldiers torturing civilian detainees, or prisoners of war, with fists, sticks, bats, water or electric shock. Journalists have documented uninvestigated war crimes, involving every active army division,^[284] including atrocities committed by Tiger Force.^[285] R. J. Rummel estimated that American forces committed around 5,500 democidal killings between 1960-72.^[30]

US forces established free-fire zones to prevent VC fighters from sheltering in South Vietnamese villages.^[286] Such practice, which involved the assumption that anyone appearing in the designated zones was an enemy that could be freely targeted, was regarded as "a severe violation of the laws of war".^[287] Nick Turse argues that a drive toward higher body counts, widespread use of free-fire zones, rules of engagement where civilians who ran from soldiers or helicopters could be viewed as VC and disdain for civilians, led to massive civilian casualties and war crimes.^[288]: 251 An example cited by Turse is Operation Speedy Express, described by John Paul Vann as "many Mỹ Lais".^[288]: 251 A report by Newsweek suggested at least 5,000 civilians may have been killed during the operation, and an official US military body count of 10,889 enemy combatants killed.^[289]

Rummel estimated 39,000 were killed by South Vietnam during the Diem-era in democide; for 1964–75, Rummel estimated 50,000 people were killed in democide. Thus, the total for 1954-75 is about 80,000 deaths caused by South Vietnam.^[30] Benjamin Valentino estimates 110,000–310,000 deaths as a "possible case" of "counter-guerrilla mass killings" by US and South Vietnamese forces.^[290] The Phoenix Program, coordinated by the CIA, was aimed at destroying the political infrastructure of the VC. The program killed 26,000-41,000 people, an unknown number were innocent civilians.^{[194]: 341–343 [291][292][293]}

Torture and ill-treatment were frequently applied by the South Vietnamese to POWs, as well as civilian prisoners.^[294]: 77 During their visit to the Con Son Prison in 1970, congressmen Augustus Hawkins and William R. Anderson witnessed detainees either confined in minute "tiger cages" or chained to their cells, and provided with poor-quality food. American doctors found inmates suffering symptoms resulting from torture.^[294]: 77 During their visits to US detention facilities, the International Red Cross recorded many cases of torture and inhumane treatment.^[294]: 78 Torture was conducted by the South Vietnamese in collusion with the CIA.^[295][296] Unlike massacres such as My Lai, media reports of torture of POWs by South Vietnamese and US forces did not generate significant public outcry in the US.^[297]

South Korean forces were accused of war crimes. One event was the 1968 Phong Nhị and Phong Nhất massacre where the 2nd Marine Brigade reportedly killed about 70 civilians.^[298] South Korean forces are accused of perpetrating the Bình Hòa massacre, Binh Tai massacre and Hà My massacre.

"The overall volume and lethality of Viet Cong terrorism rivals or exceeds all but a handful of terrorist campaigns waged over the last third of the twentieth century", based on the definition of terrorists as a non-state actor, and examining targeted killings and civilian deaths which are estimated at over 18,000 from 1966 to 1969.^[299] The Pentagon estimates the VC/PAVN conducted 36,000 murders and 58,000 kidnappings from 1967 to 1972, c. 1973.^[300] Benjamin Valentino attributes 45,000–80,000 "terrorist mass killings" to the VC.^[290] Statistics for 1968–72 suggest "about 80 percent of the terrorist victims were ordinary civilians and only about 20 percent were government officials, policemen, members of the self-defence forces or pacification cadres."^[19]: 273 VC tactics included frequent mortaring of civilians in refugee camps, and placing of mines on highways frequented by villagers taking goods to urban markets. Some mines were set only to go off after heavy vehicle passage, causing slaughter aboard packed buses.^{[19]: 270–279}

Notable VC atrocities include the massacre of over 3,000 unarmed civilians at Huế^[301] and killing 252 civilians during the Đắk Sơn massacre.^[302] 155,000 refugees fleeing the North Vietnamese Spring Offensive were reported to have been killed, or abducted, on the road to Tuy Hòa in 1975.^[303] PAVN/VC troops killed 164,000 civilians in democide between 1954-75 in South Vietnam.^[30] North Vietnam was known for its abusive treatment of American POWs, most notably in Hỏa Lò Prison (the Hanoi Hilton), where torture was employed to extract confessions.^[304]

Women were active in a variety of roles, making significant impacts and the war having significant impacts on them.^{[305][306][307]} Several million Vietnamese women served in the military and militias, particularly in the VC, with the slogan "when war comes, even the women must fight" widely used.^[308] These women made vital contributions on the Ho Chi Minh Trail, espionage, medical care, logistical and administrative work, and direct combat.^[309][310] Women took on more roles in the economy and Vietnam saw an increase in women's rights.^[311] Women emerged as leaders of anti-war campaigns and made significant contributions to war journalism.^[312]

Women still faced discrimination, and were targets of sexual violence and war crimes.^[313] Post-war, Vietnamese women veterans faced difficulty reintegrating into society and having their contributions recognised, as well as advances in rights failing to be sustained.^[314][315] Portrayals of the war have been criticised for their depictions of women, for overlooking the role women played and reducing Vietnamese women to racist stereotypes.^[316][317] Women are at the forefront of campaigns to deal with the war's aftermath, such as the effect of Agent Orange use and the Lai Đại Hàn.^{[318][319][320]}

The experience of African-American military personnel has received significant attention.^[321] Wallace Terry's work includes observations about the impacts on black servicemen. He notes the higher proportion of combat casualties among African-American servicemen, the shift toward and different attitudes of black military volunteers and conscripts, the discrimination encountered "on the battlefield, in decorations, promotion and duty assignments", as well as having to endure "the racial insults, cross-burnings and Confederate flags of their white comrades"—and the experiences faced by black soldiers stateside, during the war and afterwards.^[322]

Civil rights leaders protested the disproportionate casualties and overrepresentation in hazardous duty, experienced by black servicemen, prompting reforms implemented from 1967. As a result, by the war's completion, black casualties had declined to 13% of combat deaths, about equal to the share of draft-eligible black men, though slightly higher than the 10% who served.^[323]

Nearly all US-allied forces were armed with US weapons including the M1 Garand, M1 carbine, M14 rifle, and M16 rifle. The Australian and New Zealand forces employed the 7.62 mm L1A1 Self-Loading Rifle,^[324] with occasional use of the M16 rifle.

The PAVN/VC, although having inherited US, French, and Japanese weapons from World War II and the First Indochina War, were largely armed and supplied by China, the Soviet Union, and its Warsaw Pact allies. Some weapons—notably anti-personnel explosives, the K-50M, and "home-made" versions of the RPG-2—were manufactured in North Vietnam. By 1969 the US Army had identified 40 rifle/carbine types, 22 machine gun types, 17 types of mortar, 20 recoilless rifle or rocket launcher types, nine types of antitank weapons, and 14 anti-aircraft artillery weapons used by ground troops on all sides. Also in use, mostly by anti-communist forces, were 24 types of armored vehicles and self-propelled artillery, and 26 types of field artillery and rocket launchers.

Military deaths (1955–1975)

Year	US[325]	South Vietnam
1956–1959	4	n.a.
1960	5	2,223
1961	16	4,004
1962	53	4,457
1963	122	5,665
1964	216	7,457
1965	1,928	11,242
1966	6,350	11,953
1967	11,363	12,716
1968	16,899	27,915
1969	11,780	21,833
1970	6,173	23,346
1971	2,414	22,738
1972	759	39,587
1973	68	27,901
1974	1	31,219
1975	62	n.a.
After 1975	7	n.a.
Total	58,220	>254,256[31]: 275

Casualty estimates vary, with one source suggesting up to 3.8 million violent war deaths in Vietnam between 1955-2002.^{[326][327][328][5]} A demographic study calculated 791,000–1,141,000 war-related deaths for all Vietnam, military and civilians.^[18] Between 195,000-430,000 South Vietnamese civilians died.^{[19]: 450–453 [29]} Guenter Lewy estimated 65,000 North Vietnamese civilians died.^{[19]: 450–453} Estimates of civilian deaths caused by American bombing of North Vietnam range from 30,000^{[8]: 176, 617} to 182,000.^[20] A 1975 US Senate subcommittee estimated 1.4 million South Vietnamese civilians casualties, including 415,000 deaths.^[288]: 12 The military of South Vietnam suffered an estimated 254,000 killed between 1960-74, and additional deaths between 1954-59, and in 1975.^[31]: 275 Other estimates point to higher figures of 313,000 casualties.^{[108][44][18][45][46][47]}

The US Department of Defense figure for PAVN/VC killed from 1965 to 1974 was 950,765. Officials believed these need to be deflated by 30 percent. Lewy asserts that one-third of the reported "enemy" killed may have been civilians, concluding the figure was closer to 440,000.^{[19]: 450–453}

According to Vietnamese government figures, there were 849,018 confirmed military deaths on the PAVN/VC side,^[22][23] for the more lengthy period of 1955-75. This includes battle deaths of Vietnamese soldiers in the Laotian and Cambodian Civil Wars, in which the PAVN was a participant. Non-combat deaths account for 30-40%.^[22] However, the figures exclude deaths of South Vietnamese and allied soldiers,^[43] and the estimated 300,000–500,000 PAVN/VC missing in action. Vietnamese government figures estimate 1.1 million dead and 300,000 missing from 1945 to 1979, with approximately 849,000 dead and 232,000 missing from 1960 to 1975.^[21]

US reports of "enemy KIA", referred to as body count, were subject to "falsification and glorification", and a true estimate of PAVN/VC combat deaths is difficult to assess, as US victories were assessed by having a "greater kill ratio".^[329][330] It was difficult to distinguish between civilians and military personnel in the VC, as many were part-time guerrillas or impressed laborers who did not wear uniforms^[331][332] and civilians killed were sometimes written off as enemy killed, because high enemy casualties was directly tied to promotions and commendation.^{[225]: 649–650 [333][334]}

Between 275,000^[46]-310,000^[47] Cambodians died, including 50,000–150,000 combatants and civilians from US bombings.^[335] 20,000–62,000 Laotians died,^[44] and 58,281 U.S. military personnel were killed,^[33] of which 1,584 are still listed missing as of 2021^[update].^[336]

In July 1976, North and South Vietnam were merged to form the Socialist Republic of Vietnam.^[337] Despite speculation the victorious North Vietnamese would, in Nixon's words, "massacre the civilians there [South Vietnam] by the millions," no mass executions happened.^{[338][A 12]}

However many South Vietnamese were sent to re-education camps where they endured torture, starvation, and disease while forced to perform hard labor.^[341][342] The number involved varied depending on different observers: "... "50,000 to 80,000" (Le Monde, 1978), "150,000 to 200,000" (The Washington Post, 1978), and "300,000" (Agence France Presse from Hanoi, 1978)."^[343] Such variations are because "Some estimates may include not only detainees but also people sent from the cities to the countryside." According to a native observer, 443,360 people had to register for a period in re-education camps in Saigon alone, and while some were released after a few days, others stayed for more than a decade.^[344] Between 1975-80, more than 1 million northerners migrated south, to regions formerly in the Republic of Vietnam, while, as part of the New Economic Zones program, around 750,000 to over 1 million southerners were moved to mountainous forested areas.^[345][346] Gabriel García Márquez described South Vietnam as a "False paradise" when he visited in 1980:

The cost of this delirium was stupefying: 360,000 people mutilated, a million widows, 500,000 prostitutes, 500,000 drug addicts, a million tuberculous and more than a million soldiers of the old regime, impossible to rehabilitate into a new society. Ten percent of the population of Ho Chi Minh City was suffering from serious venereal diseases when the war ended, and there were 4 million illiterates throughout the South.^[347]

The US used its security council veto to block Vietnam's UN recognition three times, an obstacle to it receiving aid.^[348]

By 1975, the North Vietnamese had lost influence over the Khmer Rouge.^[25]: 708 Phnom Penh, Cambodia's capital, fell to the Khmer Rouge. Under Pol Pot, the Khmer Rouge would kill 1–3 million Cambodians from a population of 8 million, in one of the bloodiest genocides ever.^{[45][349][350][351]}

The relationship between Vietnam and Democratic Kampuchea (Cambodia) deteriorated. In response to the Khmer Rouge taking Phu Quoc and Tho Chu, and the belief they were responsible for the disappearance of 500 Vietnamese natives on Tho Chu, Vietnam launched a counterattack to recover the islands.^[352] After failed attempts to negotiate, Vietnam invaded Democratic Kampuchea in 1978 and ousted the Khmer Rouge, in the Cambodian–Vietnamese War. In response, China invaded Vietnam in 1979. The two countries fought the Sino-Vietnamese War. From 1978 to 1979, some 450,000 ethnic Chinese left Vietnam by boat as refugees, or were deported.

The Pathet Lao overthrew the monarchy of Laos in 1975, establishing the Lao People's Democratic Republic. The change in regime was "quite peaceful, a sort of Asiatic 'velvet revolution'"—although 30,000 former officials were sent to reeducation camps, often enduring harsh conditions.^{[120]: 575–576}

The US dropped over 7 million tons of bombs on Indochina during the war, more than triple the 2.1 million tons it dropped on Europe and Asia during World War II, and ten times the amount during the Korean War. 500 thousand tons were dropped on Cambodia, 1 million tons on North Vietnam, and 4 million tons on South Vietnam. On a per person basis, the 2 million tons dropped on Laos make it the most heavily bombed country in history, "nearly a ton for every person in Laos."^[178] Due to the particularly heavy impact of cluster bombs, Laos was a strong advocate of the Convention on Cluster Munitions to ban them, and host to its first meeting in 2010.^[353]

Former US Air Force official Earl Tilford recounted "repeated bombing runs of a lake in central Cambodia. The B-52s literally dropped their payloads in the lake." The Air Force ran many missions like this to secure additional funding during budget negotiations, so the tonnage expended does not directly correlate with the resulting damage.^[354]

Unexploded ordnance, mostly from US bombing, continues to kill, and has rendered much land hazardous and impossible to cultivate. Ordnance has killed 42,000 people since the war.^[355][356] In Laos, 80 million unexploded bombs remain. Unexploded ordnance has killed or injured over 20,000 Laotians and about 50 people are killed or maimed annually.^[357][358] It is estimated the explosives will not be removed entirely for centuries.^[201]: 317

Over 3 million people left Vietnam, Laos, and Cambodia in the Indochina refugee crisis after 1975. Most Asian countries were unwilling to accept them, many led by boat and were known as boat people.^[359] Between 1975-98, an estimated 1.2 million refugees from Vietnam and other Southeast Asian countries resettled in the US, while Canada, Australia, and France resettled over 500,000, China accepted 250,000.^[360] Laos experienced the largest flight proportionally, 300,000 out of a population of 3 million crossed the border into Thailand. Included among them were "about 90%" of Laos' "intellectuals, technicians, and officials."^[120]: 575 According to author Nghia M. Vo and the United Nations High Commissioner for Refugees (UNHCR), between 200,000 and 250,000 boat people died at sea.^[361][362]

Failure of US goals is placed at different institutions and levels. Some have suggested it was due to failure of leadership.^[363] Others point to military doctrine. Secretary of Defense Robert McNamara stated that "the achievement of a military victory by U.S. forces...was indeed a dangerous illusion."^[103]: 368 The inability to bring Hanoi to the bargaining table by bombing illustrated another US miscalculation, and the limitations of military abilities in achieving political goals.^[364] Army Chief of Staff Harold Keith Johnson noted, "if anything came out of Vietnam, it was that air power couldn't do the job."^[365] General William Westmoreland admitted bombing had been ineffective, saying he doubted "that the North Vietnamese would have relented."^[365] Kissinger wrote to President Ford that "in terms of military tactics ... our armed forces are not suited to this kind of war. Even the Special Forces who had been designed for it could not prevail."^[366] Hanoi persistently sought unification, and the effects of US bombing had negligible impact on North Vietnam's goals.^{[201]: 1–10} US bombing mobilized people throughout North Vietnam and internationally, due to a superpower attempting to bomb a society into submission.^{[201]: 48–52}

Americans struggled to absorb the lessons of the military intervention. President Ronald Reagan coined the term "Vietnam syndrome" to describe the reluctance of the public and politicians to support military interventions abroad. US polling in 1978 revealed nearly 72% of Americans believed the war was "fundamentally wrong and immoral."^[269]: 10 Six months after the beginning of Operation Rolling Thunder, Gallup, Inc. found 60% did not believe sending troops was a mistake in September 1965, and only 24% believed it was. Polling did not find a plurality believed it was a mistake until October 1967, and did not find a majority believing it was until August 1968, during the third phase of the Tet Offensive. Thereafter, Gallup found majorities believing it was a mistake through the signing of the Peace Accords in 1973, when 60% believed it was a mistake, and polls between 1990-2000, found 70% of Americans believed it was a mistake.^[367] The Vietnam War POW/MIA issue, concerning the fate of US service personnel missing in action, persisted. The costs loom large in American consciousness; a 1990 poll showed the public incorrectly believed more Americans died in Vietnam than World War II.^[368]

US expenditures in South Vietnam (1953–74)
Direct costs only^[369]

Military costs	Military aid	Economic aid	Total	Total (2015 dollars)
$111 billion	$16 billion	$7 billion	$135 billion	$1 trillion

Between 1953-75, the US was estimated to have spent $168 billion on the war (equivalent to $1.7 trillion in 2024).^[370] This resulted in a large budget deficit. Other figures point to $139 billion from 1965 to 1974 (not inflation-adjusted), 10 times education spending, and 50 times more than housing and community development.^[371] It was stated that war-spending could have paid every mortgage in the US, with money leftover.^[371] As of 2013^[update], the US government pays Vietnam veterans and their families more than $22 billion annually in war-related claims.^[372][373]

More than 3 million Americans served, 1.5 million saw combat.^[374] "At the height of American involvement in 1968, for example, 543,000 American military personnel were stationed in Vietnam, but only 80,000 were...combat troops."^[375] Conscription existed since World War II, but ended in 1973.^[376][377]

58,220 American soldiers were killed,^{[A 7]} 150,000 wounded, and at least 21,000 permanently disabled.^[378] The average age of troops killed was 23.^[379][380] Approximately 830,000 veterans, 15%, suffered posttraumatic stress disorder.^[378][381] Drug use, racial tensions, and fragging—attempts to kill officers—created problems for the military and impacted its capability.^{[382]: 44–47} 125,000 Americans left for Canada to avoid the draft,^[383] and approximately 50,000 servicemen deserted.^[384] In 1977, President Jimmy Carter granted an unconditional pardon to Vietnam draft evaders with Proclamation 4483.^[385]

The war called into question army doctrine. Marine general Victor H. Krulak criticized Westmoreland's attrition strategy, calling it "wasteful of American lives ... with small likelihood of a successful outcome."^[365] Doubts surfaced about the military's ability to train foreign forces. There was found to be considerable flaws and dishonesty by commanders, due to promotions being tied to the body count system touted by Westmoreland and McNamara.^[189] Secretary of Defense McNamara wrote to President Johnson: "The picture of the world's greatest superpower killing or seriously injuring 1,000 noncombatants a week, while trying to pound a tiny backward nation into submission on an issue whose merits are hotly disputed, is not a pretty one."^[386]

Another controversial aspect of the US effort, was use of chemical defoliants between 1961-71. 20 million gallons of toxic herbicides, like Agent Orange, were sprayed on 6 million acres of forests and crops.^[59][387] They were used to defoliate parts of the countryside to prevent the VC from hiding weaponry and encampments, and deprive them of food. Defoliation was used to clear sensitive areas, including base perimeters and ambush sites along roads and canals.^[19]: 263 The chemicals used continue to change the landscape, cause diseases and birth defects, and poison the foodchain,^[388][389] including suppressing the growth of some plants and crops and proceeding into the sediment, affecting fish and other species.^[390] US records have listed figures including the destruction of 20% of the jungles of South Vietnam and 20-36% of the mangrove forests.^[391] The environmental destruction caused was described by Swedish Prime Minister Olof Palme, lawyers, and academics as an ecocide.^{[392][393][56][394][57][395]}

The chemicals in Agent Orange^[396] pose health hazards, such as immune system disorders, developmental abnormalities, and issues with the reproductive system.^[397] Agent Orange and similar substances have caused many health issues for Vietnamese people and the US crews that handled them. Reports concluded that refugees exposed to sprays continued to experience pain in the eyes, skin and gastrointestinal upsets. In one study, 92% of participants suffered incessant fatigue; others reported monstrous births.^[398] Analysis has found significant correlation between having a parent who was exposed to Agent Orange with the likelihood of possessing or acting as a carrier of birth defects.^[399] The most common deformity appears to be spina bifida. There is substantial evidence defects carry on for three generations or more.^[400] In 2012, the US and Vietnam cooperated in cleaning toxic chemicals on Da Nang International Airport, marking the first time Washington has been involved in cleaning up Agent Orange in Vietnam.^[401] In 2018, Vietnam treated 150,000 cubic meters of contaminated soil.^[402]

Vietnamese victims attempted a class action lawsuit against Dow Chemical and other US chemical manufacturers, but a US District Court dismissed their case.^[403][404] As of 2006^[update], the Vietnamese government estimated there were over 4,000,000 victims of dioxin poisoning in Vietnam, while the Vietnamese Red Cross estimates up to one million people have health problems or disabilities as a result of Agent Orange.^[405] The US has described these figures as unreliable,^[8] and denied conclusive scientific links between Agent Orange and Vietnamese victims of dioxin poisoning. In parts of southern Vietnam, dioxin levels remain at over 100 times the accepted international standard.^[406]

The US Veterans Administration has listed prostate cancer, respiratory cancers, multiple myeloma, type 2 diabetes, B-cell lymphomas, soft-tissue sarcoma, chloracne, porphyria cutanea tarda, peripheral neuropathy as, "presumptive diseases associated with exposure to Agent Orange or other herbicides during military service."^[407] Spina bifida is the sole birth defect in children of veterans recognized as caused by exposure to Agent Orange.^[408]

The war has featured extensively in television, film, video games, music and literature. In Vietnam, the Girl from Hanoi (1974) was a film set during Operation Linebacker II, depicting wartime life. Another notable work was the diary of Đặng Thùy Trâm, a doctor who enlisted in the Southern battlefield, and was killed aged 27 by US forces. Her diaries were published in Vietnam as Đặng Thùy Trâm's Diary (Last Night I Dreamed of Peace), where it became a bestseller and was made into a film Don't Burn. The diary has been compared to The Diary of Anne Frank, and used in education.^[409]

The first major film on the war was John Wayne's pro-war The Green Berets (1968). Further films were released, the most noteworthy examples being Michael Cimino's The Deer Hunter (1978), Francis Ford Coppola's Apocalypse Now (1979), Oliver Stone's Platoon (1986) and Stanley Kubrick's Full Metal Jacket (1987). Other films include Good Morning, Vietnam (1987), Casualties of War (1989), Born on the Fourth of July (1989), The Thin Red Line (1998).^[8]

The war influenced a generation of musicians and songwriters, pro/anti-war and pro/anti-communist. The Vietnam War Song Project has identified 5,000+ songs referencing the conflict.^[410] Country Joe and the Fish recorded The "Fish" Cheer/I-Feel-Like-I'm-Fixin'-to-Die Rag in 1965, and it became one of the most influential protest anthems.^[8]

Myths play a role in the historiography of the war, and have become part of the culture of the United States. Discussion of myth has focused on US experiences, but changing myths have played a role in Vietnamese and Australian historiography. Scholarship has focused on "myth-busting",^[411]: 373 attacking orthodox and revisionist schools of historiography, and challenging myths about American society and soldiery in the war.^[411]: 373

Kuzmarov in The Myth of the Addicted Army: Vietnam and the Modern War on Drugs challenges the popular and Hollywood narrative that US soldiers were heavy drug users,^[412] in particular the notion that the My Lai massacre was caused by drug use.^[411]: 373 According to Kuzmarov, Nixon is primarily responsible for creating the drug myth.^[411]: 374 Michael Allen accuses Nixon of mythmaking, by exploiting the plight of the National League of POW/MIA Families to allow the government to appear caring, as the war was increasingly considered lost.^[411]: 376 Allen's analysis ties the position of potential missing Americans, or prisoners into post-war politics and presidential elections, including the Swift boat controversy.^{[411]: 376–377}

• List of conflicts in Asia
• Soviet–Afghan War
• Third Indochina War
• United States Army during the Vietnam War