What steps should Western border agencies take to defend their homelands from harm by Islamists? In the case of non-citizens, the answer is simple: Don't let Islamists in. Exclude not just potential terrorists but also anyone who supports the totalitarian goals of radical Islam. Just as civilized countries did not welcome fascists in the early 1940s (or communists a decade later), they need not welcome Islamists today. But what about one's own citizens who cross the border? They could be leaving to fight for the Taliban or returning from a course on terrorism techniques. Or perhaps they studied with enemies...