America had tried containment of communism in other countries such as Korea and china. America wanted to avoid the domino theory, which was if South Vietnam became communist then Cambodia, Laos, Thailand, Burma and India would all fall communist too, and if all these countries did fall, then American trading and economic interests would suffer. Therefore they had to support non-communist governments.
The government of Diem was unpopular because he was corrupt and didn’t treat the South Vietnamese people properly. The South Vietnamese would get treated better by the North Vietnam government so the NFL stepped in. The NFL aimed to overthrow Diem then get rid of the Americans and reunite North and South Vietnam. Diem tried to gain support by putting peasants in fortified villages but that made him more unpopular because the peasants did not want to be moved. The strategic hamlet programme was supposed to save the peasants from the Viet Cong, but this failed because peasants did not want to be removed from their land and the Viet Cong were promising the peasants more land once communism had taken root in the south. USA had to become more involved to stop communism spreading so Kennedy increased the number of military advisers to 100 to 1600 by 1963 and helped to equip the South Vietnamese Army. In 1961 the US spent nearly $270 million in military support for Diem. Diem’s assassination made America more involved because the communism could now spread to the south; this alarmed the American president who asked his military chiefs to formulate plans should a full-scale war break out. America had to be seen as the victim rather than the aggressor.
The assassination of Kennedy in November 1963 resulted in a more aggressive policy because Johnson took over and he had a different policy towards Vietnam because he wanted a more aggressive approach. So the new American president Johnson wanted a more aggressive war because he didn’t think the South Vietnamese government was able to keep the North Vietnamese out of the South.
The Tonkin incident in July 1964 was when North Vietnamese gunboats attacked two American ships while they were in international waters. Johnson reacted by sending 150,000 American ground troops to South Vietnam. In February 1965 air strikes had already begun on North Vietnam. This bombing was given the name ‘Operation Rolling Thunder’. This proved that America was fully committed to helping South Vietnam resist communism.
Americas most important reason for getting increasingly involved in stopping South Vietnam becoming communist was the policy of containment and the domino theory because if South Vietnam became communist then a lot of other countries would and that would mean that American trading and economics interests would suffer.
I don’t think the other two reasons were as important because they wouldn’t have much affect to the USA as the main reason.
