The U.S. has hit 85 targets in Iraq and Syria with more to come in response to last weekend’s killing of three U.S. reservists by Iran-backed militias, and it took no time for critics to declare the Biden administration’s action too weak to deter further attacks.

They’re right about that, but the belief that the answer is to bomb Iran itself is magical thinking.

Deterrence is too often seen just as a question of being tough enough: The bigger the threat or harder the hit, the greater the deterrent. But that’s as likely to force an opponent to scale their attacks up as down, because for deterrence to work, what you do is no more important than what the other side is thinking. Or as a Rand Corp. study on the issue put it, you have to understand your opponent’s "interests, motives and imperatives” and make use of those.