China had become communist in 1949 and communists were in control of North Vietnam. The USA was afraid that communism would spread to South Vietnam and then the rest of Asia. It decided to send money, supplies and military advisers to help the South Vietnamese Government.
The Vietnam War began as an outgrowth of anticolonial struggle in Asia. The defeat of the French in 1954 brought an end to French dominance in Indochina. The Western response was designed to prevent Communists from gaining control of the entire country because of his ties to the Communist Party. The U.S. began to send military advisors in the 1950's and 1960's. They also moved to set up military regimes in the South. This led to active U.S. troop involvement from the mid-1960's up to 1975.
