The United States did not get involved on a full scale until Lyndon Johnson came into office. The U.S. got involved because the French had just been defeated so they could no longer help South Vietnam. Johnson felt that South Vietnam could not go up against the Viet Cong by themselves. It worried the U.S. even more when the Viet Cong started to go full on armed conflict. American policy makers started to fear that if South Vietnam fell to communism then countries around them would start to fall to communism. They called this the Domino Theory. General MacArthur and Eisenhower disagreed and wanted President Kennedy to ignore South Vietnam. Despite their advice Kennedy increased American involvement. By the time of Kennedy's assassination there were 16,000 American troops in Vietnam. Before Kennedy's death he came up with the Strategic Hamlet Program. The program uprooted the Vietnamese peasants and moved them into camps. Many of the Vietnamese hated this because they had to leave their ancestral homes. The program in the end failed because guerrillas invaded the camps. (Keko, Don The Vietnam War (1954-1964) Examiner 20 February 2011)