If thats the case...convince China and South Korea to cut their food and energy supplies. It won't take very long for the regime to fall under its own weight.
Then what happens? Suddenly you have a bunch of loose Korean nukes that could end up anywhere in the world. In addition to that you would have a massive humanitarian crisis.
For those of you who say invade:
You have probably the most brainwashed group of people in the world in NK. They are willing to fight to the death for their regime. This isn't Iraq: NK is poorer, and the people are much more brainwashed than the Iraqis were.
This was probably the biggest foreign policy failure of the Bush administration. Just looking at everything that they have done, it is blatantly obvious they wanted to push the regime to do stuff like this. The administration is trying to play chicken with NK, and sooner or later they will run into eachother. If a small, improvrished, starving country of 23 million people can outmanuever the American Juggernaught so easily, I really wonder what a much more powerful country can do.