As a determined Tehran pursues a nuclear-weapons capability, and develops and deploys increasingly long-range ballistic missiles, a debate on the prospective role of deterrence begins to take shape. On one side is the assertion that Iranian leaders are “rational”; on the other, the fear that, when it comes to the use of nuclear weapons, they may not be. Their frequent calls for the destruction of Israel raise particular concerns in this regard.
In both policy and academic debates about deterrence, to label leaderships rational is often tantamount to declaring them deterrable. And if a leadership is deemed irrational, this is a coded way of saying that it likely cannot be deterred. But while equating “rational” with “deterrable” may make for a convenient shorthand, it is not particularly helpful in determining whether the Iranian leadership, or any other regime, is deterrable in fact.
It is a common assumption that a nuclear-armed Iran would not be a nightmare scenario because, while Iranian leaders may be eccentric, they are not suicidal. In this narrative, their fear of the consequences would deter them from using nuclear weapons or engaging in other severe provocations likely to incite Western retaliation.
This view is often backed up by the observation that even Stalin and Mao, who were considered highly eccentric, ultimately proved to be rational and deterrable. There is no reason to believe that Iran’s leaders are any more eccentric, the argument goes. Even their pursuit of nuclear weapons is explained on the basis of a rational calculation: Such weapons would give Iran both prestige and a means of deterring attacks from the West.
Confidence that Iranian leaders are rational does not directly translate into acquiescence to Iran’s goal of obtaining nuclear weapons. But, according to those who hold this view, the United States should be careful not to overreact to Iran’s nuclear program. In particular, it should avoid the use of military force. Since a nuclear-armed Iran could be deterred, why risk the consequences of using force — Iranian-sponsored acts of terror, for example, or missile attacks on U.S. military forces and U.S. allies in the region, or economic disruptions in the oil market?
The alternative narrative is that Iranian leaders have such eccentric views that they are effectively irrational. If Iranian leaders lack the good sense to fear widespread devastation and their own destruction, they might undertake extreme provocations, even in the face of possible nuclear retaliation. This description of Iranian decision-making generally accompanies the conclusion that the United States should be prepared to take great risks — and to use military force, if necessary — to prevent Iran from acquiring nuclear weapons.
The typical presumption is that any state leader sound enough to be in a position of authority must be rational, and that rational leaders can be counted on to calculate the costs of nuclear war properly. This presumption yields the comforting conclusion that deterrence will always work. It is additionally comforting in its suggestion that the United States is under little pressure to take military action, since its nuclear and conventional superiority make deterrence relatively easy. During the Cold War, this logic was one reason for the U.S. decision to forgo most strategic defenses against the Soviet nuclear threat. Why undertake the challenge of defending the American population when deterrence alone would suffice?
That Cold War line of thought can be seen in contemporary commentary on Iran and other rogue states. To wit, Iranian leaders are rational or they could not function at the level required to lead a state, and so they will be deterrable even if they acquire nuclear arms.
It is true that leaders are unlikely to be predictably deterrable if they are irrational in the sense that they suffer from a breakdown of cognition and display symptoms such as hallucinations. If Iranian leaders are so afflicted, or are eccentric enough to challenge the boundaries of reason, then the prudent course for the United States is to make deterrence, by means of both nuclear and conventional capabilities, as effective as possible, and to prepare seriously for the possibility of its failure. To do so, the U.S. should also strengthen its defensive capabilities and those of its allies, particularly its capabilities against the primary Iranian means of attack: missiles. These steps may be a hard sell in the context of austere U.S. defense budgets and the administration’s defense “pivot” toward Asia.
The alternative is to hope that Iranian leaders will be reliably deterrable or that they will decide to forgo nuclear weapons. Unfortunately, high confidence in either hope is unwarranted. We should recognize that even leaders who do not suffer from psychopathologies are often not predictably deterrable. Deterrence is a complex process that can fail for a variety of reasons. Leaders may have overriding goals — political, military, religious, ideological, or even personal — that compel them to take high-risk actions. And they may recognize the risks of provoking a powerful opponent but consider the risks of not acting to be even greater.