NORTH KOREA: The Democratic People's Republic of Korea (a.k.a., the last Stalinist nation on earth) continues to make noise as it tries to capture US attention while we're distracted by Iraq. If North Korea is going to start a shooting war, now would be the best time to do it, and they know that we know that they know this. So, Pyongyang is making threats and issuing ultimatums and, as usual, we're ignoring them. They also now claim that they aren't trying to build nukes.
Since we cut off the fuel oil supply we were bribing North Korea with (as a response to their announcement that they were, in fact, pursuing nuclear weapons), the government has become more and more desperate. Without that oil they cannot generate electricity to run their trains, transport food, heat homes, or run any sort of industry. It is only a matter of time before the government collapses, but there is one trick. If Pyongyang knows that it is about to go down, it might trigger an attack on South Korea as a last-ditch attempt at survival. This scenario is what the US is hoping to avoid by refusing to enter into negotiations. If there are no negotiations then they cannot make demands of us, and they cannot claim that we provoked them to war.
Just as we used diplomacy and the UN to lull Saddam into a sense of security so that he wouldn't attack our troops while they were being deployed, we are using diplomacy to buy time so that North Korea can fall on its own, without the need for a messy ground war.