Imagine a group of former Pentagon officials, retired senior military officers, and think tank experts gathered around a table and staring at a hexagonal map of Taiwan. Quietly they move pieces around the board: F-35 fighter jets, aircraft carriers, Marine units. Their mission is to defeat a Chinese invasion of Taiwan. War gaming has become a cottage industry inside the Beltway, led by the Pentagon and think tanks, to develop “evidence-based” strategies. Rightly, the Defense Department must study how to win against China and/or Russia in “strategic competition,” should it become a shooting war. But here’s the problem: It will...