Diplomacy is not surrender, and talking to an opponent is not a reward for good behavior. In dealings with China, Russia, or Iran, U.S. diplomatic initiatives must always be measured not by the process or optics—or by whether they support an abstract goal—but by whether the outcome results in greater or weaker constraints on a rival’s ability to harm us and our interests. Does it increase or decrease his dependency on us? Does it aid or complicate his ability to concentrate military power against us? Does it ease or impede his path of conquest?A corollary has to do with allies....