With Kiim Jong Il dying of cancer, North Korea is about to undergo its second leadership transition in its 60-year history. Speculation is that his son Kim Jong-un is hurriedly being groomed for the top job.

However, he is young and will not have the benefit of the long apprenticeship his father had. So his ability to hold onto power is open to doubt.

North Korea appears to be headed for a period of instability that will pose dangers, but also offer opportunities for positive change.

The goal of United States policy should be clear: a unified, democratic, non-nuclear Korea. The question is how to get there as quickly and safely as possible?

The problem has been that North Korea's patron, China, has not shared this goal and for two very good reasons. From China's perspective, a unified Korea means American troops on their border, and they fought the Korean War to keep them away. It also means an Asian communist dictatorship succumbing to a democratic transition, which could exacerbate political instability at home.

China's ideal outcome would be for North Korea to become more like China or Vietnam: a stable ersatz-communist dictatorship presiding over a prosperous capitalist economy that is on acceptable but not friendly terms with Washington.

The problem is: The Chinese-Vietnamese option requires a level of openness that would be fatal to North Korea. Its leaders know that if the doors to the outside world are opened and their people learn the truth about how South Korea has surpassed them in every way, their hold on power will evaporate. Once driven from power, retribution will inevitably follow, either from international tribunals or from the Korean people themselves.

To maintain the information blockade, they must maintain a hostile relationship with the outside, especially the United States. The result is an unstable prolongation of a doomed regime that depends for its existence on a constant string of crises with the outside world.

How can we get China to embrace the goal of a unified Korea ruled from Seoul? We can do little about the fears of domestic spillover. What we can do is agree to a deal in which the United States withdraws its forces from Korea upon unification, in exchange for Chinese agreement to pull the plug on Pyongyang.

China should embrace this trade for three reasons.

First, it solves a major security problem on its northeastern frontier that will improve relations with the other powers in the region and the United States. Japan would have one less reason to contemplate developing nuclear weapons.

Second, a unified Korea would be an economic powerhouse that would significantly enrich the nearby regions of China and the country as a whole.

Third, it would permanently end the refugee problem from impoverished North Korea. There would be a short-term crisis, to be sure, but the longer it is delayed the worse it will become.

The United States should embrace it because it has no positive reason to maintain troops in Korea. The deployment is a legacy of the Korean War to protect South Korea. With North Korea gone, there would be no reason for its maintenance, and the troops are sorely needed elsewhere.

We would of course retain our alliance tie with Korea to reassure Korea of its continued security and maintain regional stability.

South Korea and Japan should also embrace this deal. For the South, it fulfills the dream of reunification. Some in the South worry about the economic consequences of reunifying too quickly. But if a real opportunity arose, nationalism would trump economics as quickly as it did in Germany.

Japan would solve its most acute security problem, and it would not need to pursue nuclear weapons itself, much to its neighbors' relief.

The only losers would be the North Korean leaders themselves. However, China can help them go gently into that good night. A Chinese promise of asylum would be credible.

Chinese leaders are the last people in the world to think that the former leaders of communist dictatorships should be put on trial for human rights abuses. And if it would grease the wheels to a quick turnover of power, it would be a price well worth paying.

Andrew Kydd is an associate professor of political science at UW-Madison, specializing in international security issues.