The biggest losers are the Afghans, of course. But the entire world is less safe, less stable, and less free than it was last week. Change in world politics is not linear or steady; it can happen in lurches and sudden starts and stops. We saw in Afghanistan over the past week a dangerous bandwagon effect: Once the Afghan army refused to fight in one province and allowed the Taliban to win uncontested, it become irresistible for the next unit to do so in the next province, and the next, until the Taliban won almost without a fight.

The same dynamic can take hold in international politics. If we are so demoralized that we do not defend the free world in the next contest—in Taiwan, say, or Latvia—then it will be vastly easier not to fight the one after that, and again after that. The rest of the world will quickly believe that the free world has lost its will and the bandwagon toward an alternate vision of world order represented by China and Russia will accelerate. Then, only after all the dominos have fallen, we will have an impossible choice: Succumb to the new order, or choose to fight when it has already become vastly harder, more expensive, more lethal, and far less likely to succeed. We slide toward anarchy gradually—and then suddenly.