China's cut back their aid and have publicly expressed negative reactions to his behavior.  Since it's really between us, S. Korea, and them, China isn't going to go too far, at least yet.

Not sure how you figure upsetting Kim takes nothing more than simply existing.  We've yet to display any of that behavior.  We have bases and military all over that area.  We constantly run exercises in that area.  That isn't simply "existing".  If Russia had bases on Caribbean islands and were running military exercises in the Gulf, you think we wouldn't freak?