I agree that there is no substantive institutional framework to punish international actors, but no one is letting Kim Jung-Il sit at the cool kids table. No one wants to attack him since he can nuke South Korea and/or Japan, but at the same time... he's mostly ignored. I don't see any countries' governors in a panic over this.
Sure, you can send them to their rooms, but now they've got DVD players and video games and god knows how many toys in there. How is that punishment?
The U.N. gets on your ass if you try to impose any real discipline, like bombing their nuclear facilities. "It might cause psychological damage in the long run!" they say.
Well, when North Korea is all grown up and is out robbing liquor stores and breaking into your house, I bet you'll wish you'd given it the belt when it had a chance to learn right from wrong.