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.
1965 in the Vietnam War Vietnam was a matter of much debate. One U.S. government estimate was that the Viet Cong army consisted of 40,000 full-time fighters and 80,000 to 100,000 part-time guerrillas. The Department of Defense's fact book estimated that the Viet Cong numbered less than 200,000 plus 39,175 political cadre. These numbers presumably included thousands of fighters and cadre infiltrated from North Vietnam during the previous five years. The first North Vietnamese army units dispatched to South Vietnam, consisting of three regiments (about 5,000 men), had arrived in South Vietnam in late 1964. A junior-level CIA analyst, Samuel A. Adams, had just begun