
Reasons for U.S. Involvement
- After the French defeat at Dien Bien Phu (1954), the U.S. feared that Southeast Asia might fall to communism, following the Domino Theory.
- The Geneva Accords (1954) temporarily divided Vietnam at the 17th parallel, creating a communist North (Ho Chi Minh) and an anti-communist South (Ngo Dinh Diem).
- The U.S. refused to sign the accords, seeing elections as a risk for communist victory; it began funding and training the Army of the Republic of Vietnam (ARVN).
- Under Eisenhower and Kennedy, involvement grew through military advisors and financial aid, not direct combat.
The 1954 Geneva Accords
- A series of agreements that ended the First Indochina War and established a framework for peace in Vietnam, Laos, and Cambodia.
The Domino Theory and the Cold War (1950s–1970s)
Background and Origins
- The Domino Theory emerged during the early Cold War as a key idea behind U.S. foreign policy.
- It was first articulated by President Dwight D. Eisenhower in 1954, after the communist victory in Vietnam’s anti-French war.
- The theory suggested that if one country in a region fell to communism, neighboring nations would soon follow, like a row of falling dominos.
- It reflected the growing U.S. fear of Soviet expansion in Asia, Latin America, and beyond.
Application During the Cold War
- The theory guided U.S. involvement in Korea (1950–1953) and later in Vietnam (1955–1975), where American leaders feared a communist takeover would spread across Southeast Asia.
- In Latin America, the Domino Theory justified U.S. intervention in Guatemala (1954) and Cuba (1961) to prevent Soviet influence in the Western Hemisphere.
- The U.S. supported anti-communist governments and military dictatorships, seeing them as necessary to stop “the first domino” from falling.
- It also led to massive military spending and long-term commitments that shaped the Cold War balance of power.
Impact and Legacy
- The Domino Theory led the U.S. into costly and unpopular wars, particularly in Vietnam, where the fear of communism outweighed local realities.
- In Southeast Asia, some countries (like Laos and Cambodia) did experience communist movements, partly confirming the theory, but others, like Thailand and Malaysia, did not fall.
- In Latin America, the theory justified decades of U.S. intervention and support for repressive regimes, fueling anti-American sentiment.
- By the 1970s, critics argued that the theory oversimplified complex regional issues, turning political struggles into global ideological battles.
Nature of U.S. Involvement (Escalation and War Stages)
- Early Escalation (1961–1965)
- President John F. Kennedy increased the number of U.S. advisors to over 16,000 and supported Diem’s government despite corruption and unpopularity.
- After Diem’s assassination (1963), instability in South Vietnam led to greater U.S. involvement.
- The Gulf of Tonkin Incident (1964) allowed Lyndon B. Johnson to expand the war, authorizing direct combat with the Gulf of Tonkin Resolution.

- Full-Scale War (1965–1968)
- The U.S. launched Operation Rolling Thunder, a major bombing campaign, and deployed over 500,000 troopsby 1968.
- The Viet Cong, backed by North Vietnam and the USSR, used guerrilla warfare, tunnels, and surprise attacks like the Tet Offensive (1968) to wear down U.S. morale.
- Heavy civilian casualties and media coverage turned public opinion in the U.S. against the war.
- Vietnamization and Withdrawal (1969–1975)
- Under Richard Nixon, the U.S. shifted to Vietnamization, gradually withdrawing U.S. troops while increasing South Vietnam’s responsibility.


