OSS was operating in French Indochina - in support of Ho Chi Minh and General Giap - during World War II and we never really left.
It would be fascinating to be able to have a human historical simulator and see how things would have turned out if we had backed Vietnamese nationalism in 1945 like we had originally intended before we had to begrudgingly back French colonialism in order to keep them on our side against the Soviets. I can’t think of anything the French did that was helpful, and picking up the mess they created to keep Vietnam as a colony cost us dearly.
Ho Chi Minh was always a Communist and a Comintern agent. There was no way he wasn’t going to support the Soviets.
We had an adviser killed there 1948.