First, North Korea’s threat to the United States is not static; it is ratcheting up dangerously with new nuclear, missile and miniaturization technology that for the first time will allow Pyongyang to reach U.S. shores. This alone argues for a new approach. If the president can avoid triggering a preemptive war (a nightmarish prospect that should be dealt with carefully), then his tough rhetoric could force Kim to reckon with an outcome beyond sanctions, which haven’t changed his course and almost certainly will not in the future.

Second, stability-obsessed China is primed to hear this message, and altering its behavior may be the most important objective. Beijing is Kim’s lifeline, accounting for more than 90 percent of North Korea’s trade. Yet China’s leaders have done little more than wrist-slap their neighbor to the east for two decades — including, this year, a painful but not fatal constriction of coal and oil trade and the removal of North Korean businesses from China. It’s fair to conclude, after all this time, that Beijing is not going to change course unless it foresees a real possibility of war. The Chinese know that this would result in the collapse of their only real ally in East Asia, a reunited and vastly more powerful Korea allied with Washington, and a formidable refugee and humanitarian crisis on their border.