History of Vietnam since 1945 unstable as no government could keep power for long. There were more coups, often more than one every year. The Communist-run Viet Cong expanded their operation and scored some significant military victories during this period. In 1965, US President Lyndon Johnson sent troops to South Vietnam to secure the country and started to bomb North Vietnam, assuming that if South Vietnam fell to the Communists, other countries in the Southeast Asia would follow, in accordance with the domino theory. Other US allies, such as Australia, New Zealand, South Korea, Thailand, the Philippines, and Taiwan also sent troops to South Vietnam.
Vietnam War ended direct U.S. involvement in the Vietnam War, created a ceasefire between North Vietnam/PRG and South Vietnam, guaranteed the territorial integrity of Vietnam under the Geneva Conference of 1954, called for elections or a political settlement between the PRG and South Vietnam, allowed 200,000 communist troops to remain in the south, and agreed to a POW exchange. There was a sixty-day period for the total withdrawal of U.S. forces. "This article", noted Peter Church, "proved… to be the only one of the Paris Agreements which was fully carried out." All US forces personnel were completely withdrawn by March 1973. In