During the early 1960s, the U.S. military presence in Vietnam escalated as corruption and internal divisions threatened the government of South Vietnamese President Ngo Dinh Diem.

After World War II, the French tried to re-establish colonial control over a region known as French Indochina—today the countries of Vietnam, Cambodia, and Laos. Following the defeat of the French, Vietnam was partitioned by the Geneva Accord of 1954 into Communist North Vietnam and non-Communist South Vietnam. The United States supported a military government in the South and the decision of its leader, Ngo Dinh Diem, to prevent free elections, which might result in the unification of the country under the control of the Communists. Guerilla forces supported by the Communist government of the North initiated a series of attacks in South Vietnam, and the Geneva Accord began to crumble.

The Domino Theory

American foreign policy after World War II was based on the goal of containing Communism and the assumptions of the so-called "domino theory"—if one country fell to Communism, the surrounding countries would fall, like dominoes. In response to that threat, the Southeast Asia Treaty Organization (SEATO) was formed in 1955 to prevent Communist expansion, and President Dwight D. Eisenhower sent some 700 military personnel as well as military and economic aid to the government of South Vietnam. The effort was foundering when John F. Kennedy became president.

Internal Divisions

Corruption, religious differences, and mounting successes by the Vietcong guerrillas weakened the South Vietnamese government of Ngo Dinh Diem. Diem was Catholic, and public protests over the repression of Buddhists threatened the stability of his regime. Kennedy accelerated the flow of American aid and gradually increased U.S. military advisers to more than 16,000. At the same time, he pressed the Diem government to clean house and institute long-overdue political and economic reforms.

The situation did not improve. In September of 1963, President Kennedy said in an interview, "In the final analysis, it is their war. They are the ones who have to win it or lose it. We can help them, we can give them equipment, we can send our men out there as advisers, but they have to win it, the people of Vietnam, against the Communists... But I don't agree with those who say we should withdraw. That would be a great mistake... [The United States] made this effort to defend Europe. Now Europe is quite secure. We also have to participate—we may not like it—in the defense of Asia."

The Overthrow of Diem

A few weeks later, on November 1, 1963, the South Vietnamese government was overthrown. The coup had the tacit approval of the Kennedy administration. President Diem was assassinated, after refusing an American offer of safety if he agreed to resign.

In the final weeks of his life, President Kennedy wrestled with the future of the United States' commitment in Vietnam. Whether he would have increased military involvement or negotiated a withdrawal of military personnel still remains hotly debated among historians and officials who served in the administrations of President Kennedy and President Lyndon B. Johnson.

A Domino Falls

United States military aid to Vietnam increased during 1964. By 1965, President Johnson authorized US troops to begin military offensives and started the systematic bombing of North Vietnam. By 1968, the number of US forces surpassed 500,000. During that year's presidential campaign, Americans were deeply divided by the deteriorating military and political situation in Vietnam.

In May 1968, President Johnson announced that formal peace talks would soon begin in Paris. The talks stalled during the last eight months of Johnson's presidency, and the deadlock continued during the early years of Richard Nixon's administration. Finally, in January 1973, an agreement was reached, and President Nixon ordered an end to all US offensive actions against North Vietnam.

In January 1975, North Vietnam began massive invasions of South Vietnam. A few months later, the North Vietnamese captured the capital city of Saigon, and the last Americans were evacuated from the US embassy. The American war in Vietnam was over. More than 3 million Vietnamese and 58,000 Americans had lost their lives.