Well, if George Kennan's theory of containment had worked better, they might not have had to go to Vietnam. China might not have been communist, nor Cuba. Because if America had been able to contain communism like the plan was designed to do, Russia would have never been able to spread its infectious communism, thus, no communism in Vietnam, thus, no Vietnam War. The problem with containment, though, was that the only way we would have really been able to contain it was through a hot war, and if that had happened, well, the nuclear weapons might have been used. What we tried to do was cut USSR off economically with the Marshall Plan, which gave monetary aid to those who had been ravaged by the war. However, we didn't offer it to Russia because they were communists. That didn't work, so instead of fighting the USSR, we decided to try to contain communism.