Switching from deterrence to compellence is a high-risk move. Deterrence is about preventing behavior; compellence is about changing behavior, a much more difficult business, since keeping the status quo by threats is generally easier than changing the status quo by force. The target of compellence must either comply or inflict more pain in return.
The Iranians, however, chose neither to fold nor to fight. They took a narrower path, opting for a more calibrated response by launching ballistic missiles that damaged U.S. bases but avoided human casualties. In so doing, the Iranians accomplished several objectives.
David Frum: We’re just discovering the price of killing Soleimani
First, they satisfied the domestic need for immediate action. There was no way the Iranians could promise covert or proxy action as a response to the killing of someone as prominent as Soleimani. They had to demonstrate to loyal citizens that they would act, and to dissident citizens that they did not fear the Americans. The United States directed the killing of Soleimani, and so the missile strikes were directly and publicly attributable to Iran—as the Iranian regime intended them to be.
Second, Iran showed that it was willing to roll with changes in the rules of the game. As Leon Panetta said on Meet the Press the day after the Iranian strikes, the Obama administration never considered taking out Soleimani, because the risk of war simply wasn’t worth it. Likewise, Iran had avoided the use of ballistic missiles against any other state since the Iran-Iraq War. The Americans showed that they were willing to kill senior Iranians. The Iranians showed in return that they were willing to use ballistic missiles, and that next time they might not be targeted to miss.
Third, the strikes were a signal to Iraq, and to other nations in the region, that association with the Americans does not confer some magical immunity. Indeed, they demonstrated that allying with the U.S. is a risk in itself.
A related point is that Iran wisely avoided inflicting U.S. casualties, which would have united even skeptical Americans behind Trump and likely would have forced him to act. (The chairman of the Joint Chiefs of Staff, General Mark Milley, claims that the Iranians had intended to inflict casualties. This is hard to believe, given the pattern of the damage, and contradicts other sources in the administration.) Even advisers who might have earlier tried to sway Trump away from killing Soleimani would have been unable to argue against a significant military response.
Finally, instead of inflicting casualties, the Iranians gave the Americans a plausible way out of a crisis Trump created. They made their point, and then signaled to American decision makers (or at least to those who understand how to read such signals) that they were willing to let the exchange stop. Obviously, this was in Iran’s interest; an escalation to all-out war would lead to an Iranian loss, if by “loss” we mean greater casualties before the termination of hostilities. But Tehran was betting that, absent immediate U.S. deaths, Washington does not have the stomach for a bigger fight, and it was right.
Following the U.S. retaliation against Soleimani, the Iranians were faced with the tasks of restoring their own credibility as a military opponent and averting further U.S. action. They accomplished both, at least for now. The U.S. bid for compellence failed; the Iranian attempt to restore deterrence succeeded.