@Lash,
I think it's too early to tell, the North Koreans could mean business but they could also try to con the orange conman. Their idea is probly to trap him somehow, to push a few painful buttons, me think. They have some trump card (pun non intended) they want to play, in order to get massive concesions. Could be some damaging hacked intell as they did against Sony, or anything. But they will come to the meeting with a surprise.
Evidently nobody knows what they have up their sleeve if anything, but I don't trust their bona fide. Trump should go in that meeting with no expectation for an easy deal, and prepared instead for a HUUUUGE load of bizarro stuff, a massive need for poker face and face saving. And of course it wouldn't hurt to go in there with some cards up the US sleeve as well, by that I mean a few credible threats and counter-intell to push back on what NK may have.