On September 11, 2001, when I taught my third class as a professor of East European history at Yale, I knew what the subject had to be: provocation. The Russian imperial secret services, and then the Soviet secret services, had perfected the art of convincing adversaries to do what they wanted them to do while making them think it was for their own reasons. When something terrible happens, as it had that day, suffering, though no doubt desired by those who caused it, is not the point. The point is to get you into a frame of mind that leads...