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.
Australian Army Training Team Vietnam later. Serong would later be seconded, and in one capacity or another would remain in Vietnam until the fall of Saigon in 1975, serving as a senior advisor to both the US and South Vietnamese governments. On arrival, the unit joined a large group of US advisors and were dispersed across South Vietnam in small groups. Three groups were dispatched to South Vietnam's northern provinces, training members of the Army of the Republic of Vietnam (ARVN) at the National Training Centre at Dong Da and South Vietnamese Regional Forces (RF) at Hiep Khanh, while a fourth was based at the