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.
1968 in the Vietnam War President Lyndon Johnson addresses the nation, announcing steps to limit the war in Vietnam and reporting his decision not to seek reelection. The speech announces the first in a series of limitations on US bombing, promising to halt these activities above the 20th parallel. United States Secretary of Defense Clark Clifford gets the President to authorize 24,500 more troops on an emergency basis, raising authorized strength to the Vietnam War's peak of 549,500, a figure never reached. Operation Toan Thang I was a US and ARVN operation conducted between 8 April 1968 and 31 May 1968. Toan Thang, or "Complete