The North Korean nuclear threat is a “hinge” moment for the United States and China, and for the new international order both nations say they want.

If Washington and Beijing manage to stay together in dealing with Pyongyang, the door opens on a new era in which China will play a larger and more responsible role in global affairs, commensurate with its economic power. If the great powers can’t cooperate, the door will slam shut — possibly triggering a catastrophic military conflict on the Korean Peninsula.

President Trump’s bullying style, even in dealing with trivial matters of domestic politics, obscures the extent to which he has tried to marry U.S. policy on North Korea with that of China. For the most part, he has been surprisingly successful. Beijing and Washington have mostly been aligned, as in this past weekend’s unanimous U.N. Security Council vote in favor of additional sanctions against Pyongyang to punish its continued missile tests.