Ten years ago, I joined a U.S. trade delegation for the chance to visit, as a journalist, a remote part of China that borders both North Korea and Russia. As we traveled around, local Chinese greeters proudly pointed out the contrasting vistas: rugged empty hills in North Korea and isolated clusters of Soviet-era buildings in Russia, whereas in China, commerce and construction abounded between booming border towns. In one such town, Hunchun, population 250,000, regional officials asked me if I planned to write anything. Perhaps...