Interesting post, Republic.  Who's RFD?  Oh, maybe FDR? Regardless, I think "single-handedly" is a stretch. Whoever was President in 1941 had a little nudge from the Japanese...  

"JFK got involved in Cuba" (Bay of Pigs, I assume): And he vowed he'd never, ever do such a thing again. Bitterly regretted it; bitterly angry at those who persuaded him.  Given that, how do you think he felt about Vietnam?

In the fall of 1963, when Kennedy died, the CIA was on the ground in Vietnam, and so were about 16,000 "non-combat" military personnel. 122 were killed that year. About 3 weeks before Kennedy died, a military-led coup ousted corrupt, despotic President Diem. Suffering Buddhists were jubilant. The U.S. had no direct involvement in the coup, At one point it appeared US was willing to provide President Diem transportation to escape--which the CIA urged him to do. He was slow to do it. Transportation never materialized and Diem was captured and assassinated.