Beijing condemns Pyongyang's nuclear program but doesn't exercise its extraordinary leverage, notably supplying 90%-plus of the North's energy and substantial amounts of food and humanitarian aid. China's real fear is that pressuring the North could cause the regime to collapse, creating two threats: a flood of impoverished Korean refugees into northeastern China and American troops on its Yalu River border.
Both fears are exaggerated. First, Washington, Seoul and Tokyo should make it clear that they would do everything possible to prevent or mitigate a refugee crisis following the collapse of the North Korean state. That is desirable on humanitarian grounds alone, but also because North-South integration would proceed more beneficially from thorough planning to stabilize the North's population in place and to provide adequate assistance after the Kim regime collapses.