Thrawn, if you step back you'll realize you are arguing a lost point.
The UN cannot mount a major military operation without US participation. Period.
Now, things can go along quite nicely without us if only "peacekeeping" operations are required in places that have basically a "small arms" situation/problem.
However, using Kuwait as the most recent example of something outside of a "small arms situation", it's clear that removing a mechanized aggressor from an invaded country cannot be done without US participation.
A Korean scenario would be far worse than Kuwait.
The UN can handle "small arms" without us. The world might stumble along just fine for a while but eventually some loony-toon would get the idea that there's no one to stop him. He'd be right, of course. And then the party would be on again all around the world.