The thing NK doesn't have is the ability to implement a MAD policy. Even if they could nuke Seattle or another Pacific coast city (Seoul is way more likely than the US), they would be sacrificing their country in an instant. I don't think the leadership is that disconnected from reality, even if Kim Jong Il was (but even that needs to be questioned, because despite the rhetoric he never attacked SK). They have too much to lose. I think they want a bomb to deter an invasion.
Like I said, NK doesn't scare me at all, and it's most likely nothing more than political posturing. I don't think they pose a threat to anyone at this time. Was just explaining to the parent comment that they do have a very offensive rhetoric which makes them different from other nuclear countries. Though their track record shows they probably won't ever use them or try to attack SK outside of little skirmishes once every 10 years. So I completely agree. Best case scenario would be attacking South Korea and causing some major damage to Seoul and other areas within artillery range, but their country and all of it's forces would be glassed within 24 hours of them going on any major offensive. Other countries wouldn't even use nukes on them even if NK used them, they wouldn't be needed. We have multiple carrier groups in the region. They wouldn't make it through the night if they chose to attack anyone. So I completely agree they have too much to lose. At best they could inflict damage on Seoul and maybe the US in a few years time, but that would mean utter destruction of their entire military equipment, troops, and everyone involved in the regime. But, I always wonder if they just are delluded enough to do something crazy someday. Or if one of these days when they decide to shell some islands or small villages, that SK fires back, and then NK fires back, and they actually do feel backed into a corner and call for full attack on the South. I think that scenario is extremely unlikely, but who knows. There's a lot of itchy trigger fingers on both sides of that DMZ.I think they want a bomb to deter an invasion.
China is condemning this most recent test even, which is unusual for them. Even they are finally taking an international stance that they aren't behind them anymore. China IS too smart for that.