Policy Analysis No. 583

The Bottom Line on Iran: The Costs and Benefits of Preventive War versus Deterrence

Executive Summary

It appears increasingly likely that the Bush administration’s diplomatic approach to Iran will fail to prevent Iran from going nuclear and that the United States will have to decide whether to use military force to attempt to delay Iran’s acquisition of a nuclear weapons capability. Some analysts have already been promoting air strikes against Iran, and the Bush administration has pointed out repeatedly that the military option is “on the table.” This paper examines the options available to the United States in the face of a prospective final diplomatic collapse.

Evaluating the two ultimate options—military action on the one hand and acceptance and deterrence on the other—reveals that neither course is attractive. However, the evidence strongly suggests that the disadvantages of using military action would outweigh those of acceptance and deterrence. Attacking Iran’s nuclear program would pose several problems: U.S. intelligence seems likely to be even poorer on Iran than it was on Iraq; Iran has hardened and buried many nuclear facilities in a way that would make them difficult to destroy; Iran could respond in such a way that the United States would feel forced to escalate to full-blown regime change; and there would be a host of unintended consequences inside and outside Iran.

A policy of acceptance and deterrence is also an unattractive prospect. Iran would likely be emboldened by the acquisition of a bomb and could destabilize the region and inject more problems into an already bleak prospect for peace between the Israelis and Palestinians. Still, given the costs of the military option, the only compelling rationale for starting a war with Iran would be if there were good reason to believe that the Iranian leadership is fundamentally undeterrable. But available evidence indicates that Iran is deterrable and would be particularly so if faced with the devastating repercussions that would result from the use of a nuclear weapon. Therefore, the United States should begin taking steps immediately to prepare for a policy of deterrence should an Iranian bomb come online in the future. As undesirable as such a situation would be, it appears less costly than striking Iran.

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Justin Logan is a foreign policy analyst at the Cato Institute.