How did the threat of atomic warfare affect President Truman's Policy of Containment?

Basically, it just made him have to be more
careful.

If there were not a threat of having a nuclear
war, it would be much easier to threaten the Soviet Union and to take chances in trying
to drive the Soviets out of a particular place where they were trying to
expand.

However, if there is the chance of nuclear war, you
have to be a lot more careful.  If all weapons are conventional, you can have a small
battle here or there without too much risk.  But if you have nukes, any battle can
become a really horrifying war.