How wrong this assessment was is now clear for everyone to see. A week ago, the U.S. said Afghanistan could withstand the Taliban for 90 days. Today, the (70,000-strong) Taliban is in control of the capital, the much-vaunted Afghan army has disintegrated, and tens of thousands of Afghans – whose collective force could stop the Taliban, if only it had the organization to do so – are fleeing to any place and by any means they can. Conventionally, the United States did everything right; it installed a government, equipped and trained an army with four times the Taliban’s manpower, an...