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.
CIA activities in Vietnam A series of accusations in the early 1970s that the CIA was complicit in drug trafficking in Laos was a contributing factor in the public's opposition to US activities in Southeast Asia. Neither the CIA nor any of its officers were accused of direct activity in the narcotics operations, and it is likely that the agency did not focus much energy on the trafficking by indigenous allies until a heroin epidemic broke out among US troops in South Vietnam. There was nothing preventing the hill tribes in northern Laos from producing and selling opium until 1971, as the trade was