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 Adams' iconic image of South Vietnamese General Nguyễn Ngọc Loan's execution of a Viet Cong operative was taken in 1968. The year also saw Walter Cronkite's call to honourably exit Vietnam because he thought the war was lost. This negative impression forced the US into the Paris peace talks with North Vietnam. US troop numbers peaked in 1968 with President Johnson approving an increased maximum number of US troops in Vietnam at 549,500. The year was the most expensive in the Vietnam War with the American spending US$ (US$ in 2019) on the war. The year also became the deadliest