Domino Theory
Following China’s fall to the Communists in October 1949 the U.S. was determined to prevent any further expansion of Communism in Asia. American foreign policymakers believed that the fall of Indochina would probably lead to the toppling of neighbouring countries such as Thailand, Burma, Malaysia, Indonesia and the Philippines.
This belief underlay President Truman’s decision in 1950 to supply aid to France in its fight against the
Viet Minh. The Domino Theory also strongly influenced President Kennedy’s move in 1961 to substantially increase America’s advisory commitment to South Vietnam and President Johnson’s 1965 decision to bomb and commit ground troops.
See
SEATO