My North Korean Theory

Precisely...Every move he makes is calculated to ensure that HE stays in power. Kim wants to remain in power and wants to feel powerful. He rattles his sabre every so often to make sure that the world thinks of him. It makes him feel like a big shot...even though he's starving his country and everyone there is scared of him.

To the poster who mentioned "a few low yield nukes:" China doesn't want any nukes anywhere near their border. A low yield nuke is still a nuke and the ENTIRE WORLD would look down upon that sort of move. You see, this is where it gets tricky... A simple false flag...and airburst of a nuke could turn the entire world against the US; this is why we have no choice but to be calm and in many cases, ignore the "fat neighbor." I wouldn't put it past him to detonate a dirty bomb on his own shores, if tensions escalate. (Yes, nukes have very identifiable signatures...so he would need to make it a dirty bomb with low levels of radiation so that he can safely blame whichever nuclear capable country he is against that day.)