After President John F. Kennedy's assasination, Lyndon B. Johnson inherited the United States' conviction to prevent the fall of Vietnam to the communists. There were 16,000 military "advisors" in the country when Johnon took office. During his presidency, however, the United States was drawn increasingly deeper into the conflict in Southeast Asia. By the end of 1965, 184,000 American troops were in Vietnam. The number reached 385,000 in 1966. The war ultimately lasted over a decade, and it cost Americans $150 billion and 58,000 lives. The political turmoil that resulted from the conflict in Vietnam toppled the Johnson administration and undermined the effectiveness of many of the president's Great Society social programs.