How and why did the us become involved in Vietnam?

"Actually, the war was fought from 1960-1975.

The Americans joined the French in the war because they thought that it would keep Asia from becoming Communist."

Actually that's wrong, the war was fought fron 1965-to 1971.

They became involved due to the Domino theory, being that if Vietnam falls to communism, so will all the rest of the surronding Asian countries, so on and so forth. The Americans saw an ally in the french in the fight against communism, and supported them.