How so? What do you expoect China to do vis-avis N. Korea?
Same as us, lean on him; covertly threaten Jong-Ill with the possibility of a joint American-Chinese military reaction to any N. Korean nuclear aggression.
Behind us, China is the only remaining superpower in the world, and the possibility of retaliation or reaction from Korea's stronger nation to the North is a useful bargaining tool. I think that this possibility (however slight) is the unspoken "elephant in the room" that Bush is using to make certain that Kim doesn't leave the table for good.