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; the South Vietnamese army was supported by the United States, South Korea, Australia, Thailand and other anti-communistallies. 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 states in 1975.
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 Việt Cộng, 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 B. Johnson authorization 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 Tết Offensive, U.S. 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 modeled on heavy fire-power focused doctrines modeled 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 U.S. 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 Việt Cộng 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 sides 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.
Various names have been applied to the conflict. Vietnam War is the most commonly used name in English. It has also been called the Second Indochina War and the Vietnam Conflict.
As there have been several conflicts in Indochina, this particular conflict is known by the names of its primary protagonists to distinguish it from others. In Vietnamese, the war is generally known as Kháng chiến chống Mỹ (Resistance War Against America), but less formally as 'Cuộc chiến tranh Mỹ' (The American War). It is also called Chiến tranh Việt Nam (The Vietnam War).