The Vietnam War (Vietnamese: Chiến tranh Việt Nam), also known as the Second Indochina War, and in Vietnam as the Resistance War Against America (Vietnamese: Kháng chiến chống Mỹ) or simply the American War, was a conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955[A 1] to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vietnam and the government of South Vietnam. The North Vietnamese army was supported by the Soviet Union, China and other communist allies and the South Vietnamese army was supported by the United States, South Korea, Australia, Thailand and other anti-communist allies. The war is considered a Cold War-era proxy war by some US perspectives. The majority of Americans believe the war was unjustified. The war would last roughly 19 years and would also form the Laotian Civil War as well as the Cambodian Civil War, which also saw all three countries become communist regimes in 1975.
There are several competing views on the conflict, with some on the North Vietnamese and National Liberation Front side viewing the struggle against US forces as a colonial war and a continuation of the First Indochina War against forces from France and later on the United States especially the light of the failed Geneva Conference calls for elections. Other interpretations of the North Vietnamese side include viewing it as a civil war especially in the early and later phases following the U.S interlude between 1965 and 1970 as well as a war of liberation. The perspective of some Provisional Revolutionary Government of the Republic of South Vietnam, the successor to the Viet Cong were motivated in part by significant social changes in the post-WW2 Vietnam, and had initially saw it as a revolutionary war supported by Hanoi The pro-government side in South Vietnam viewed it as a civil war, a defensive war against communism or were motivated to fight to defend their homes and families. The U.S. government viewed its involvement in the war as a way to prevent a communist takeover of South Vietnam. This was part of the domino theory of a wider containment policy, with the stated aim of stopping the spread of communism.
Beginning in 1950, American military advisors arrived in what was then French Indochina.[A 3] Most of the funding for the French war effort was provided by the U.S. The Viet Cong, also known as Front national de libération du Sud-Viêt Nam or FNL (the National Liberation Front), a South Vietnamese communist common front aided by the North, fought a guerrilla war against anti-communist forces in the region, while the People's Army of Vietnam, also known as the North Vietnamese Army (NVA), engaged in more conventional warfare, and had launched armed struggles from 1959 onward. U.S. involvement escalated in 1960 under Kennedy, with troop levels gradually surging under the MAAG program, from just under a thousand in 1959 to 16,000 in 1963.
By 1964 there were already 23,000 U.S troops involved, but this escalated further following the 1964 Gulf of Tonkin incident, in which a U.S. destroyer was alleged to have clashed with North Vietnamese fast attack craft. This was followed by the Gulf of Tonkin Resolution, which gave Lyndon Johnson authorisation to increase U.S. military presence, deploying for the first time ground combat units and increasing troop levels to 184,000. Every year onward there was significant build-up despite little progress, with Robert McNamara, one of the principle architects of the war begin to express doubts of victory by the end of 1966. U.S. and South Vietnamese forces relied on air superiority and overwhelming firepower to conduct search and destroy operations, involving ground forces, artillery, and airstrikes. In the course of the war, the U.S. conducted a large-scale strategic bombing campaign against North Vietnam. Following the Tet Offensive, US forces begun withdrawal under the Vietnamization phase, while Army of the Republic of Vietnam unconventional and conventional capabilities increased following a period of neglect and became modelled on heavy fire-power focused doctrines modelled after US Forces.Operations crossed international borders: bordering areas of Laos and Cambodia were used by North Vietnam as supply routes and were heavily bombed by U.S. forces.
Gradual withdrawal of U.S. ground forces began as part of "Vietnamization", which aimed to end American involvement in the war while transferring the task of fighting the communists to the South Vietnamese themselves and begun the task of modernising their armed forces. Morale declined significantly among US forces during the wind-down period and incidents of fragging, drug-use and insubordination increased with General Creighton Abrams remarking "I need to get this army home to save it". From 1969 onwards the military actions of the Viet Cong insurgency decreased as the role and engagement of the NVA grew. Initially fielding less conventional and poorer weaponry, from 1970 onward the People's Army of Vietnam and its branch People's Liberation Armed Forces of South Vietnam had increasingly became mechanised and armoured, capable of modernised combined arms and mobile warfare and begun to widely deploy newer, untested weapons. These two side would see significant, rapid changes throughout its lifetime from their original post-colonial armies, and by mid-1970s the ARVN became the fourth largest army with the PAVN became the fifth largest army in the world in two countries with a population of roughly 20 million each.
Despite the Paris Peace Accord, which was signed by all parties in January 1973, the fighting continued in the "war-of-the-flags" period in which both Saigon and Hanoi attempted to take territory before and after the accord and the ceasefire was broken just days after its signing. In the U.S. and the Western world, a large anti-Vietnam War movement developed as part of a larger counterculture, the largest such anti-war movement up to that point in history. The war changed the dynamics between the Eastern and Western Blocs, and altered North–South relations, and had significantly influenced the political landscape in the United States, across much of Western Europe and U.S ground-force intervention spurred the rise of transnational political movements and campaigning.
All air-force and naval units and all other forces were completely withdrawn in 15 August 1973. The capture of Saigon by the North Vietnamese Army in April 1975 marked the end of the war, and North and South Vietnam were reunified the following year. The war exacted a huge human cost in terms of fatalities (see Vietnam War casualties). Estimates of the number of Vietnamese soldiers and civilians killed vary from 966,000 to 3.8 million. Some 275,000–310,000 Cambodians, 20,000–62,000 Laotians, and 58,220 U.S. service members also died in the conflict, and a further 1,626 remain missing in action.[A 2] The Sino-Soviet split re-emerged following the lull during the Vietnam War and ties between the DRV and its Cambodian allies in the Royal Government of the National Union of Kampuchea, the newly formed Democratic Kampuchea begun almost immediately in a series of border raids by the Khmer Rouge and erupted into the Cambodian–Vietnamese War, with Chinese forces directly intervening in the Sino-Vietnamese War. The end of the war and resumption of the Third Indochina War would precipitate the Vietnamese boat people and the bigger Indochina refugee crisis, which saw an estimated 250,000 people perish at sea.