A stitch in time saves nine. Pay me now or pay me later. Ukraine shows that failing to deter Russia before its February 2022 invasion has proven far more costly than active deterrence would have been. American foreign policy in Asia needs to learn lessons from this failure. Chaos is displacing the stable global order that has been led by the United States since World War II. Active American leadership is required or worse will come. Yet a powerful segment of our political class apologizes for the good we have done for three-quarters of a century and defaults to a passive and reactive foreign policy, thinking it reduces risk. Despite grousing by adversaries and some friends, when the U.S. leads, the world is a more peaceful and prosperous place. The word “isolationism” is overused these...