Perhaps no other country has more to lose from North Korea's acquisition of a sizeable nuclear arsenal than China. The existence of such weapons would not only endanger the city of Beijing but also provoke a regional arms race in which Japan, South Korea, and possibly even Taiwan would eventually develop their own strategic deterrents. Given these facts, it is surprising that China has not acted more forcefully to persuade Pyongyang to terminate its nuclear program.

The explanation for this reluctance is the importance Beijing attaches to regional stability. If the North Korean regime were to collapse, a refugee crisis would ensue as starving people flooded across the border into northeastern China, and the way would be opened for South Korean and American troops to advance up the peninsula towards Beijing.

If the Bush administration wants to enlist Chinese help against Pyongyang, therefore, it must first assuage these very reasonable concerns.

China's importance to the United States stems from the absence of other sources of leverage over Pyongyang. Military action against North Korea is an unattractive option because Kim Jong Il and his generals could retaliate massively. Promises of long-term economic aid in exchange for Pyongyang's renouncing its nuclear aspirations also offers little hope. Kim has a long record of consenting to such deals and then surreptitiously reviving his armament efforts.

What is needed is an intermediate form of suasion. China is the only power that possesses this sort of leverage. According to South Korean analysts, in 2002 China supplied 31 percent of North Korea's imports and accounted for 37 percent of its exports. In addition, each year Beijing gives several hundred thousand tons of food aid to its troublesome neighbor, and, now that the United States and Japan have suspended their oil shipments, provides the preponderance of its fuel.

Beijing has occasionally used its influence to express discontent with North Korean behavior, and, by all accounts, the diplomatic dialogue between the two states has also become more acrimonious of late.

However, Beijing will presumably not press Pyongyang much further unless it is assured of the Bush administration's goodwill. In practice, this means that Washington must identify and alleviate China's specific geopolitical concerns. If Beijing fears a refugee crisis, then the United States and its allies must promise to help finance the care of the displaced and perhaps to absorb some significant number of North Korean emigrants. If Beijing fears the approach of American military forces, Washington should consider promising to limit U.S. activities north of the demilitarized zone.

While demonstrating that the United States is willing to accommodate China's needs, the Bush administration must also prove that Pyongyang's policies represent an immediate threat to East Asian stability. To do this, Washington needs to engage more frequently and more conciliatorily in diplomatic talks with Kim and his representatives. For with each abortive discussion, each rejection of reasonable American gestures, the North Koreans push Beijing closer to the conclusion that they pose an unacceptable danger to China's national security interests.

The effect of this policy of dual engagement with China and North Korea would almost certainly be positive. As Beijing's attitude towards Pyongyang hardened, the world might see a sharp reduction in its oil shipments, the deployment of more troops to the North Korean border, or overt discussions with the United States about the future of the peninsula. This would be the strongest possible signal to Pyongyang, short of war, that the world will not tolerate its emergence as a major nuclear power. If, on the other hand, he remained intransigent until the intensified pressure caused North Korea to collapse, Washington and Beijing would still be relatively well situated to deal with the ensuing challenges.

It is through the joint resolution of serious challenges that potential rivals like the United States and China learn to trust each other. If there is a silver lining to the North Korean cloud, it is this opportunity to improve bilateral communications in anticipation of future exigencies.

The writer is a fellow at the Asia-Pacific Research Center, Stanford Institute for International Studies.