Why did the USA enter the Vietnam War?

Shahid H. Raja
4 min readNov 2, 2021


The Vietnam War which lasted from 1955 to 1975 was fought between North Vietnam (supported by the Soviet Union, China, and North Korea) and South Vietnam (supported by the United States, Thailand, Australia, New Zealand, and the Philippines.) While the Viet Cong (also known as the National Liberation Front, or NLF), a South Vietnamese communist force helped by the North fought a guerilla war against the anti-communist forces in the South, the North Vietnamese Army engaged in a more conventional war, at times putting large forces to battle.


The Vietnam War was an unfinished agenda of the past. The French colonized Vietnam, Cambodia, and Laos in the late 18th century but lost control of these colonies to Japan during WW2 when it was occupied by Germany. However, Viet Minh, a Communist-led common front under the leadership of Ho Chi Minh started an armed struggle to oust the Japanese with the support of the USA, USSR, and China.

When WWII ended and Japan lost these territories, France tried to recolonize them but had to meet huge resistance from the local population under the leadership of Ho Chi Minh. Thus started the 1st Indo-China War in December 1945

It gained momentum when in January 1950, China and the Soviet Union recognized the Viet Minh’s Democratic Republic of Vietnam, based in Hanoi, as the legitimate government of Vietnam. Soon afterward, the United States and Great Britain recognized the French-backed State of Vietnam in Saigon, led by former Emperor Bảo Đại, as the legitimate Vietnamese government.

The Korean War of 1950 accentuated the Cold War rivalry between the communist bloc led by the USSR and the capitalist bloc led by the USA. Vietnam too became a part of this Cold War. Chinese started assisting Viet Minh to turn their forces into a regular army; the USA started advising the South and training their army. It is estimated that the USA spent a billion dollars to support the French during the period 1950–54

However, the French surrendered and signed the Geneva Peace Accord in 1954 which ended the 1st Indochina War. Besides granting independence to Cambodia and Laos, Vietnam was temporarily partitioned at the 17th Parallel into North Vietnam where Ho Chi Minh, a communist became the president, and South Vietnam where Bao Dai remained the emperor while Ngo Dinh Diem, a catholic anti-communist became the Prime Minister. This Partition was supposed to be temporary till 1956 when elections were to be held and Vietnam unified.

Diem turned out to be a ruthless tyrant who did not hold elections in 1956 as agreed and started arresting communist sympathizers to stay in power. Resistance against his rule resulted in the formation of NLF aka Viet Cong in Cambodia in 1960. Major support for the Viet Cong was from the peasants of the South, who were unhappy with the reversal of land reforms by Diem.

Why did the USA enter the Fray?

Several explanations have been given for the entry of the USA into this conflict. Some of these are as follows

1. Commitment to France

During the final stages of World War 2, the USA told Great Briton that they shouldn’t expect to get their empire back after the war but didn’t tell France the same thing. Reason? President Charles de Gaulle of France is reported to have insisted on American help in Southeast Asia as a quid pro quo for its joining NATO. Were it not for the Cold War, the French would possibly have quietly packed up and left, and the Americans would never have gotten involved.

2. Domino Theory

The Domino Theory postulated that if communism took hold in Vietnam, it would spread to other countries. It was fuelled by the McCarthyism Madness of the fifties within the USA. Consequently, the United States started supporting the anti-communist government in South Vietnam by first sending military advisers to help train and support the South Vietnamese army to fight against the Viet Cong.

When it failed, the USA started sending its regular forces in the 1960s, which remained in Vietnam till its humiliating defeat in 1975. Once in, getting out was a political quagmire. Anyone leaving Vietnam to the communists would have ended their political career. Nixon said he was moving forward while moving backward

3. The Hegemonic Theory

America, at that time, was one of the two hegemons (the other being Russia) and she considered herself the leader of the free world. As a hegemon, it was important for the USA to keep iterating her powerful position by increasing her sphere of influence and protecting her allies. Abandoning South Vietnam was therefore problematic, since America had, by then, engaged herself in several alliances. It needed the trust of other allies in her, to keep having allies. Since she had aligned herself with France first, and later with South Vietnam, it was highly significant for her to keep pushing in and not show any weakness. Because of this, it continued getting involved more and more in the war.


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