China should have enormous leverage with regimes like those in Khartoum and Pyongyang. But does Beijing have the political will to use it?

Once again Beijing is swarming with diplomatic motorcades, convoys of sleek black sedans fluttering flags and getting special treatment from traffic police. The occasion: a new round of the Six-Party Talks aimed at defusing the North Korean nuclear crisis. Never before in the history of discussions, which began three years ago, have they triggered such palpable optimism. These great expectations are based on promising developments—such as a bilateral U.S.-North Korea meeting in Berlin recently to discuss Washington’s crackdown on Pyongyang’s financial transactions—that followed North Korea’s first nuclear test late last year. Are the negotiators on the verge of a breakthrough?