Reuters

Through no fault of any individual, the logic of counterterrorism verges toward totalitarianism. National-security officials can keep us safe from a surprise attack by the Russians or Chinese by keeping tabs on a small number of foreign elites. Asking them to keep us safe from any terrorist attack is a radically different proposition.

Thus the dangers of a national-security state focused on terrorism. Vanishingly few individuals have the desire to carry out a terrorist attack, but virtually everyone has the means to do so. If the goal is to be zero terrorist attacks, there is a certain logic in attempting to conduct surveillance on literally everyone on earth. Little wonder that the NSA is doing so much to invade privacy at home and abroad. Its very mission tends to prevent its leadership—and presumably many of its employees—from more fully tempering their actions, in accordance with the recognition that a free society which values privacy and liberty will always be vulnerable to terrorism. The threat can't be eliminated at a cost worth bearing. If we strike the proper balance, the NSA will sometimes fail in its mission.

That is tragic. But America had better face up to that reality, because General Keith Alexander and his supporters won't do so, and the only alternative is much more grim: much less liberty in a state where national-security officials are more free to act without constraints ... but where terrorism happens anyway, as any Russian will attest.