Trump is playing a bluffing strategy and risking not being believed, having his bluff called, or triggering over reaction from North Korea or China and making things worse. He is right on the edge now so we need to just keep our fingers crossed. HIs bluff is to keep China on his side and be more active against North Korea because of concern over his subtle threats and his concessions to China on trade (which Trump can yank if China does not play ball). Trump knows China is the only one who can push NK to back off and go to the negotiating table. But this is close because NK just stopped communications with Chinese officials. Trump will also need to give some carrots to NK and not just the big stick (which would be almost suicide for us to actually use).