"kid asking if he could go steal a car"
Not a bad way to put it.
One school of thought notes that Stalin had just gotten the bomb, and then got a little cocky about poking the U.S.
It's amazing what kind of crap goes down when people get it into their heads that the U.S. isn't going to retaliate.
In any case, it's obvious that military action drove back the communists, and the result was a South Korea that had decades of prosperity instead of being a gulag like the north.