My guess on North Korea is that the regime is on the verge of collapse, so ill Il is giving it his all to pressure the US into bilateral talks to try to get concessions out of us -- as they've successfully done in the past with our last couple of Democratic presidents -- to try to maintain his grip of power on the country. A few billion from us, in keeping with the Clinton model, would probably go a long way for him.
Unless he's really really crazy, Il doesn't believe the line about wanting nukes to protect himself from the US, as he's done the math as well as we have and concluded that it doesn't make sense to invade. He could try to surreptitiously get nukes into the hands of terrorists to try to attack us directly indirectly, but declaring to the world that he has nukes undermines that purpose as he'll be the first one we go after should we be attacked that way.
Recent announcements have an air of desperation to them. I can't imagine him thinking that he'll benefit from starting an all-out nuclear war (though that's not to say he wouldn't use nukes if he'd already decided he'd lost control over his country), so I read the desperation as meaning his country is going to collapse on its own relatively soon.
It'll be interesting to watch this play out -- yet again I'm glad Bush is in office because he's handling it the right way: no bilateral talks, and no concessions. Though, additional options like a naval blockade to further the collapse of the country may make sense. We'll see what happens.
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North Korea calls for ban on 'Team America' in Czech Republic