ANSWER -
The United States became involved in the Vietnam War in the early 1960s as part of its Cold War strategy to contain the spread of communism. Initially, the U.S. provided military advisors and equipment to the South Vietnamese government to help fight against the communist Viet Cong guerilla fighters and the North Vietnamese army. Over time, the U.S. military presence in South Vietnam increased, and in 1964, Congress passed the Gulf of Tonkin Resolution, which authorized the U.S. military to take more aggressive actions against North Vietnam.
By 1965, U.S. combat troops were deployed to South Vietnam, and the conflict escalated into a full-scale war. The United States believed that it was necessary to stop the spread of communism in Southeast Asia, but the war was widely unpopular at home, and the U.S. eventually withdrew its troops in 1973. The conflict ended in 1975 with the fall of South Vietnam to the communist forces.