American involvement began in the early years of the Cold War. Involvement was based on President Truman’s “policy of containment”. Eisenhower, describe the domino theory in south east Asia as “ If you have a row of dominoes and knock over the first one then they will all fall down”. Southeast Asia was given the domino theory because; if the Asian nation fell under communism then the ones around it would also fall. The communist takeover on Vietnam could pose a threat to Cambodia, Laos, Burma, and Thailand.