Brink Lindsey writes in NRO that the barbarians are at the gates once again.

We face, now and for the foreseeable future, the threat of a new barbarism. The new barbarians, like those of old, consist of groups in which every member is a potential warrior. Like their predecessors, the new barbarians rely on their ability to outmaneuver their civilized adversaries, to concentrate deadly force at vulnerable spots. But unlike the old steppe nomads, the new barbarians seek neither booty nor conquest. Our new barbarian adversaries pursue a strategy of pure and perfect nihilism: They seek destruction for destruction's sake. Their strategy, in other words, is terrorism.