Learn about the war that enmeshed the United States in a battle against communism in Southeast Asia for more than twenty years.


  • The Vietnam War was a prolonged military conflict that started as an anticolonial war against the French and evolved into a Cold War confrontation between international communism and free-market democracy.
  • The Democratic Republic of Vietnam (DRV) in the north was supported by the Soviet Union, China, and other communist countries, while the United States and its anticommunist allies backed the Republic of Vietnam (ROV) in the south.
  • President Lyndon Johnson dramatically escalated US involvement in the conflict, authorizing a series of intense bombing campaigns and committing hundreds of thousands of US ground troops to the fight.
  • After the United States withdrew from the conflict, North Vietnam invaded the South and united the country under a communist government.

Origins of the war in Vietnam

The origins of American involvement in Vietnam date back to the end of the Second World War, when the Vietnamese were struggling against the continued French colonial presence in their country. Ho Chi Minh, the leader of the Viet Minh (Vietnamese Independence League) and the founder of Vietnam’s Communist Party, successfully blended nationalist, anti-French sentiment with Marxist-Leninist revolutionary ideology. In 1954, after a prolonged guerrilla war to liberate Vietnam, the Viet Minh captured Dien Bien Phu, and decisively routed the French.1^1
Map of Vietnam. The red line indicates the separation between North and South Vietnam following the peace negotiations in Geneva in 1954. Before the country was unified under the North Vietnamese government in 1975, Ho Chi Minh City was named Saigon. Map of Vietnam adapted from Wikimedia Commons.
In peace negotiations at Geneva, the decision was reached to divide Vietnam into northern and southern halves. The communists, headed by Ho Chi Minh, would govern the northern half, with its capital at Hanoi, while South Vietnam, with its capital at Saigon, would remain non-communist. The Soviet Union and the People’s Republic of China supported the north, while the United States was determined to maintain an independent, non-communist South Vietnam.
In December 1960, the National Liberation Front, commonly called the Viet Cong, emerged to challenge the South Vietnamese government. A civil war erupted for control of South Vietnam, while Hanoi sought to unite the country under its own communist leadership. The Second Indochina War began in earnest with the US commitment to prevent the communists from overrunning South Vietnam. In spring 1961, the administration of John F. Kennedy expanded US support for the South Vietnamese government, including an increase in US military advisers, the doubling of military assistance, and authorization of the use of napalm, herbicides, and defoliants.2^2
The escalating US involvement in Southeast Asia was driven by the logic of the domino theory, which contended that the falling of one country to communism would result in other surrounding countries succumbing to communism, much as one toppled domino will take down others in a row. The containment strategy, laid out by George Kennan in the Long Telegram, dictated that the United States do everything in its power to prevent the spread of communism. US officials believed that if South Vietnam fell to communism, so would the surrounding countries of Indonesia, Thailand, Burma, Malaysia, Laos, and Cambodia.

Lyndon Johnson and the war in Vietnam

In August 1964, the US government received word that two North Vietnamese torpedo boats attacked US destroyers in the Gulf of Tonkin. President Lyndon Johnson requested authorization from Congress for the use of military force, resulting in the Gulf of Tonkin resolution, which laid the groundwork for the full-scale US military commitment to Vietnam. The resolution declared the support of Congress for “all necessary measures to repel any armed attack against the armed forces of the United States and to prevent further aggression.”3^3
Eighty-eighth Congress of the United States of America
Begun and held at the City of Washington on Tuesday, the seventh day of January, one thousand nine hundred and sixty-four
Joint Resolution
To promote the maintenance of international peace and security in southeast Asia.
Whereas naval units of the Communist regime in Vietnam, in violation of the principles of the Charter of the United Nations and of international law, have deliberately and repeatedly attacked United Stated naval vessels lawfully present in international waters, and have thereby created a serious threat to international peace; and
Whereas these attackers are part of deliberate and systematic campaign of aggression that the Communist regime in North Vietnam has been waging against its neighbors and the nations joined with them in the collective defense of their freedom; and
Whereas the United States is assisting the peoples of southeast Asia to protest their freedom and has no territorial, military or political ambitions in that area, but desires only that these people should be left in peace to work out their destinies in their own way: Now, therefore be it
Resolved by the Senate and House of Representatives of the United States of America in Congress assembled,
That the Congress approves and supports the determination of the President, as Commander in Chief, to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.
Section 2. The United States regards as vital to its national interest and to world peace the maintenance of international peace and security in southeast Asia. Consonant with the Constitution of the United States and the Charter of the United Nations and in accordance with its obligations under the Southeast Asia Collective Defense Treaty, the United States is, therefore, prepared, as the President determines, to take all necessary steps, including the use of armed force, to assist any member or protocol state of the Southeast Asia Collective Defense Treaty requesting assistance in defense of its freedom.
Section 3. This resolution shall expire when the President shall determine that the peace and security of the area is reasonably assured by international conditions created by action of the United Nations or otherwise, except that it may be terminated earlier by concurrent resolution of the Congress.
Johnson was motivated by both domestic political and international balance of power considerations. He fully subscribed to the domino theory and to the containment strategy, and also feared appearing weak in the eyes of his domestic political opponents.4^4
In 1965, Johnson dramatically escalated US involvement in the war. He authorized a series of bombing campaigns, most notably Operation Rolling Thunder, and also committed hundreds of thousands of US ground troops to the fight. Fearful that the war would jeopardize his domestic agenda, Johnson concealed the extent of the military escalation from the American public.5^5
President Lyndon Johnson awards a medal to an American soldier during a visit to Vietnam in 1966. Image courtesy Wikimedia Commons.
The 1968 Tet Offensive, a bold North Vietnamese attack on the south, convinced many US officials that the war could not be won at a reasonable cost. Heightened opposition to the war was one of the major factors in Johnson’s decision not to run for re-election in 1968.

Richard Nixon and Vietnam

Richard Nixon campaigned for the presidency with a “secret plan” to end the war in Vietnam. Once in office, his administration sought to achieve “peace with honor.” Nixon ultimately expanded the war into neighboring Laos and Cambodia, while simultaneously encouraging the “Vietnamization” of the war effort, which entailed the gradual withdrawal of US troops and an increasing reliance on the South Vietnamese armed forces. By the end of 1969, the number of American troops in Vietnam had been cut in half.6^6
The Paris Peace Accords established the terms according to which the last remaining US troops in Vietnam would be withdrawn. In 1975, the North Vietnamese finally achieved the objective of uniting the country under one communist government. The Socialist Republic of Vietnam was formally established on July 2, 1976, and Saigon was renamed Ho Chi Minh City. Though the outcome of the war was a clear defeat for the United States, the countries surrounding Vietnam did not subsequently fall to communism, demonstrating the flawed reasoning of the domino theory.
The war in Vietnam had lasting consequences for US foreign policy. Congress passed the War Powers Act in 1973, in a clear attempt to reassert a measure of control over the making of foreign policy and to impose constraints on presidential power. For well over a decade, American public opinion was hostile to the idea of foreign interventions. This was known as the “Vietnam syndrome,” and it entailed an unwillingness to become bogged down in foreign wars in which American national security interests were unclear.

What do you think?

Why did the United States become involved in Vietnam?
What were the assumptions underlying the US involvement in Southeast Asia? Were they correct?
Was the war in Vietnam a civil war or a global Cold War confrontation?
Article written by Dr. Michelle Getchell. This article is licensed under a CC-BY-NC-SA 4.0 license.
  1. For more on the origins of US involvement, see Mark Atwood Lawrence, Assuming the Burden: Europe and the American Commitment to War in Vietnam (Berkeley: University of California Press, 2005) and Mark Atwood Lawrence, The Vietnam War: A Concise International History (New York: Oxford University Press, 2008).
  2. See William S. Turley, The Second Indochina War: A Concise Political and Military History (Lanham, MD: Rowman & Littlefield, 2009); Lawrence, The Vietnam War, 71-73.
  3. The exact circumstances of the Gulf of Tonkin incident, and the extent to which US officials may have misrepresented the incident, remain in dispute. Tonkin Gulf Resolution; Public Law 88-408, 88th Congress, August 7, 1964; General Records of the United States Government; Record Group 11; National Archives.
  4. For more on Lyndon Johnson and the Vietnam War, see Michael H. Hunt, Lyndon Johnson’s War: America’s Cold War Crusade in Vietnam, 1945-1968 (New York: Hill and Wang, 1997).
  5. Paul S. Boyer, Promises to Keep: The United States since World War II (Boston, MA: Houghton Mifflin, 1999), 283-284.
  6. Lawrence, The Vietnam War, 143.
Full text of the Gulf of Tonkin resolution courtesy the Our Documents initiative.