why did the US decide to intervene in the Vietnam War?
Answers
At the beginning, Vietnam was relatively worthless in terms of Domino Theory. At least just a sideshow. The main circus somewhere else. Commies struggles went big in Malaysia where British troops must jump in, in Indonesia where Suharto killed 2 million Indonesian commie sympathizers and collaborators, in Singapore where Lee Kan Yew seceded it from Malaysia due to the fears of commies and in Laos where the Soviet Air force operated a largest airlift in the history of Red Army. Eventually the circus had closed for good
After failing to spread communism to the countries mentioned above, the USSR started looking for an alternative. Vietnam the only place left untouched, so the Soviet would like to re-run the communism-expanding program in SEA one more time. Meanwhile the US just reacted to the evens with overwhelmed power. They did not even think thoroughly how to win the war. Defoliation, search and destroy, pacification and carpet bombings actually all copied from the UK. CIA had proposed an winning strategy but it also ignored.
Just remember that the USSR tricked the US into Vietnam War. Unlike Korea War where Stalin not bother much and had the soviet troops went to Korea things could have been worst for the UN Coalition. Brezhnev had scrutinized the US fighting in Korea for years, then he concluded that he could have been able to make the US hurt in Vietnam.
b. US policy-planners feared a spread of communism to other countries in the area, that is it would have a domino effect.
c. US entry into the Vietnam war was the outcome of humiliating defeat of the France, a European country, at the hands of a small Asian country Vietnam.
d. The unification of the North and south Vietnam which was in violation of Geneva convention was closely watched by US which feared the rising power of the communist.
e. Ideological differences that prevailed with US representing capitalist bloc and Vietnam communist ideology
hope it helps