Xi Jinping has watched a long line of U.S. politicians demand that China clean up the North Korean weapons mess. If he happened to be watching the first Presidential debate last week, when the Republican nominee did so in characteristically forceful terms, the Chinese President might be forgiven for leaning forward to ask his television set a rhetorical question: “What’s in it for me?”

Most Americans have little time for the Chinese Communist Party’s self-interest in North Korea; still less do they try to see things from Xi Jinping’s perspective. And these are probably reasons why the convergence of U.S. and Chinese interests with respect to North Korea is so rare.