The papers are full of scary scenarios about what Iran will do to Israel or to the U.S. if Israel attacks Iranian factories producing nuclear weapons. The CIA is reported to be worrying about Iranian attacks on US military forces, on Saudi oil facilities, and a variety of other potential targets of terrorism or missile attack. The extreme discussions of Iranian lashing out seem to assume that deterrence against Iran would be eliminated by the Israeli attack. But why should that be?
Should we assume that Iran now refrains from attacks against Israel and the U.S. only because it believes such attacks are illegal or immoral? Or is it possible that Iran decides how much it should use terror and other measures against Israel and the US at least partly by concern about what would happen to it if it dared such attacks? And wouldn't such concern continue--or even increase--after Iran suffered an attack?
There are several reasons why Iran's calculation about what it has to be deterred from doing would change if its nuclear factories were destroyed. But it is not likely that they will lose control of themselves from anger or humiliation. Their incentives are likely to be altered much more than emotion reduces their ability to calculate their interests. It is quite possible that the effectiveness of American and Israeli deterrence will be reduced by the destruction of Iranian nuclear factories, but it is unlikely that such deterrence will be eliminated--especially if Israel and the U.S. try to protect themselves by speaking and acting in ways that maximize deterrence.
If Israel decides to bomb the Iranian nuclear complex it would probably be wise not to use all its force in a single raid. It would need to make it clear to Iran that it is prepared to destroy additional targets in Iran if Iran attacks Israeli civilians. Perhaps to emphasize how severely Israel will punish Iran if Iran retaliates by attacking Israeli civilians Israel should hint that it would not respond if Iran retaliated in kind by attacking Israel's nuclear facilities. Of course Israeli and Iranian values are different, so Israeli deterrence should focus not on attacks against Iranian civilians but on targets that the Iranian regime cares about, specifically targets that would weaken the regime's control of the country and its military power.
The U.S., of course, is in a much stronger position. It can make it clear to the Iranian regime that attacks against U.S. targets might well lead to a U.S. attack which would cripple the Iranian military and security apparatus, and perhaps destroy its ability to provide fuel for Iranian vehicles. Even if Israel destroys a number of Iranian nuclear sites the U.S. would continue to favor a new Iranian regime, so Iran would have reason to avoid giving the U.S. an excuse for destroying its ability to terrorize its own citizens.
If Iranian nuclear facilities were destroyed by Israel Iran would have strong new incentives to attack Israel and the U.S., and this might be enough to overcome some deterrence. Some response would be necessary for the Iranian regime to maintain self-respect and to show the Iranian people that the regime continued to be capable of protecting itself. And the regime has made many threats which would be exposed as idle bluffs if it did not respond. Furthermore, as the victim of an attack Iran would for a while have a kind of political license to do things that normally would produce at least a political backlash.
Therefore we need to assume that Iran would make at least some violent responses if its nuclear facilities were attacked. That is, our deterrence would be at least temporarily weakened. But it is probably wrong to think that after it was attacked Iran would simply run wild, wreaking massive destruction on Israel, the U.S., and perhaps Saudi Arabia and Western oil consumers, limited only by its capacity to produce harm.
If Iran's initial destructive reaction to being attacked is met first by strong warnings, and quickly by retaliatory actions, it is likely that Iran will sharply limit its violence. It will want to do more, but it will have to live with the fact of its fragility and limited power.
This is not an argument that no one will be hurt by Iranian retaliation if Iran is attacked, much less is this is an argument that Iran should be attacked. We should not carried away by dramatic imaginings of all that Iran might do to hurt us. But nobody can know for sure how Iranians will react, and no one can predict where a chain of violence will lead once it is started. The point is only to remind ourselves that the question of deterrence does not end once an attack is made, and of the value of escalation dominance, and of the desirability of not reducing deterrence by speaking in advance as if it didn't exist.