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.
1959 in the Vietnam War States Army historian said, "Bolstered by some $190 million a year in American military and economic aid, Diệm enforced at least a degree of governmental authority throughout South Vietnam. His regime resettled the refugees, achieved a measure of economic prosperity, and promulgated what was, on paper, a progressive land reform policy. By means of a series of harsh and indiscriminate but effective anti-Communist 'denunciation' campaigns, Diệm made progress in destroying the remaining Viet Minh organization in the countryside. His troops kept the surviving sect and Communist guerrillas on the run, and his government attempted to establish mass organizations of its