Structures of Deterrence
As with the broader policy of containment, the vast literature of Cold War deterrence provides a useful framework for thinking about deterring a nuclear Iran. The nature of the Iranian regime is much different than the Soviet regime, and the extent of Iranian power is a fraction of Soviet power, but while the particular circumstances may be unique, there are structural similarities.
What is deterrence? In a classic 1983 study, John Mearsheimer defined it broadly as “persuading an opponent not to initiate a specific action because the perceived benefits do not justify the estimated costs and risks.”31 A decade later, Paul Huth, Christopher Gelpi, and D. Scott Bennett adopted a similar definition: deterrence is a “policy that seeks to persuade an adversary, through the threat of military retaliation, that the costs of using military force will outweigh the benefits.”32 Samuel Huntington observed that retaliatory or preemptive capabilities were useful in creating offensive or counteroffensive military options even within a defensive strategic posture.33 This also brings forth the distinction between deterrence based upon denial and deterrence by threat of punishment. Indeed, the original US Cold War strategy embraced both means of deterrence, as Dean Acheson wrote in Power and Diplomacy:
We mean that the only deterrent to the imposition of Russian will in Western Europe is the belief that from the outset of any such attempt American power would be employed in stopping it, and if necessary, would inflict on the Soviet Union injury which the Moscow regime would not wish to suffer.34
As the size of the Soviet nuclear arsenal grew and the costs of a nuclear exchange, even if it seemed to achieve its military objectives, grew intolerable, late in the Cold War deterrence came to be synonymous with denial. Yet it is worth recovering these important nuances in thinking about deterring Iran. If nothing else, deterrence by threat of punishment is a more economical approach to employing military force than deterrence by denial.
What is common to these traditional definitions is that deterrence is seen as a subjective measure: its value can be understood only in terms of the state of mind it creates in the mind of an adversary. The adversary must be persuaded. Estimated costs must outweigh perceived benefits. Thus the military bean count—the objective reckoning of the correlation of forces—is only a part of the deterrence equation. Likewise the operational calculus, the likely performance of forces in combat that includes not just the capabilities of their weaponry but the training, doctrine, and other less-tangible military capacities of the forces, is not fully determinative of any deterrent effect. Nonmilitary factors have an equal, if not greater, weight. Thus Mearsheimer refines his definition:
Decision makers might well assess the probable reaction of allies and adversaries, aspects of international law and possible reaction in a forum such as the United Nations, the likely effect upon the economy. In short, deterrence broadly defined is ultimately a function of the relationship between the perceived political benefits resulting from military action and a number of nonmilitary as well as military costs and risks.35
Even this expanded definition does not deal directly with domestic political calculations, which often are the most powerful determinants of all involved. These domestic variables also call into question another basic tenet of deterrence theory as practiced during the Cold War: that states are unitary rational actors—that is, that national decision making is generally coherent (unitary) and motivated by comprehensible calculations of risk and reward (rational). Although there was a school that recognized a distinct Russian or Soviet strategic culture (and even, occasionally, a glimmering that the United States viewed the world through a unique set of lenses produced by its principles and its history), more frequently it was assumed that both sides operated from a clear understanding of material national interest. Indeed, much US policy proceeded from the premise that Americans might better appreciate Soviet interests than the Russians themselves. Despite the effort put into “Kremlinology”—charting the rise and fall of individuals and factions within the bureaucracy—there was an analogous premise that when a Soviet premier spoke or negotiated seriously, he acted in the name of the state. Both these assumptions remain deeply entrenched in the views of the US policymaking establishment. Brzezinski’s argument for containing Iran allowed that Iranians “may be dangerous, assertive, and duplicitous, but there is nothing in their history to suggest they are suicidal.”36
Surveying the political science literature of the Cold War years suggests eight general questions that frame the calculation of deterrence.37
•The Polarity Question. Where do the two (or more) parties stand in the constellation of the international system? Current conventional wisdom is that the post–Cold War “unipolar moment” of US dominance is coming to its conclusion.38 Two trends point in this direction: the rise of new great powers with global interests and the perceived withering of the state in light of increased globalization. Despite these broad trends, for the purposes of assessing the policy of Iran containment, the United States still should be regarded as the principal architect of international security while Iran’s overall standing is that of a relatively weak regional power.
•The Interest Question. What are the two sides’ relative strategic interests? Past literature is likewise only partially useful in assessing the scope of relative interests in the twenty-first century. Political science has posited a strong correlation between the strength of the national interests at risk in a dispute or the proximity of the battlefield with the willingness to accept risk. However, there is a strong tendency to reify strategic interests, whereas a more important question may be how each side perceives its interests, including its ideological interests. In general terms, we assume that the United States will conceive its Iran policies in light of its global strategy and its long-standing commitment to securing a favorable balance of power in the Persian Gulf region. Conversely, we see Iran’s nuclear ambitions as an expression of its desire to establish a very different balance of power that suits its geopolitical and ideological interests. That is, the behavior of both the United States and Iran—their own assessments of their interests—will be shaped to some degree by fundamental beliefs about the nature of a just international order.
•The Involvement Question. How do the two sides’ roles in other conflicts or confrontations affect the prospects for deterrence? The professional literature asserts that when challengers are involved in a third-party dispute, they are less likely to take additional risks or escalate conflicts; conversely, if the challenger sees that a defender is occupied elsewhere, this will appear as an opportunity to exploit. Answering this question in the context of Iran deterrence will be a delicate calculation. Both the United States and Iran already have many intertwined involvements throughout the Persian Gulf region and beyond. The United States in particular has a long habit of multiple involvements in disparate regions. In recent years, Iran has been active globally, courting a variety of partners, including some—like Venezuela—in South America. In sum, both Iran and the United States are involved with many third parties, simultaneously defending and challenging each other’s interests. Answering the involvement question will be a complex assessment.
•The Risk Question. Are the parties likely to be risk averse or willing to run risks? There are two elements to the risk question: one is structural, reflecting the nature of the international system, and the other is cultural, reflecting the nature of the competing states. A multipolar system is not only inherently less stable, but also creates opportunities for risk takers. As the number of actors in the international system rises—states, coalitions of states, or even nonstate actors—it often becomes harder to predict or to calculate the likely outcome of a conflict or the behavior of the larger number of actors. The character of states and actors tends to become more pronounced: risk takers become bolder while status-quo, risk-averse states become more cautious. In a multipolar world, risk takers see greater opportunities and more likely rewards while the risk averse feel more
constrained and more at risk. Thus the strategic culture question takes on increased importance. The nature of the competing regimes is given greater play.
•The Dispute-Behavior Question. How does each party’s behavior in recent conflicts and the perceptions of that behavior add or detract from deterrence? In addition to the structural question of risk taking within the international system, there is the question of each party’s track record, that is, its actual and perceived exercise of political willpower. Deterrence literature concludes, not surprisingly, that backing down in a public dispute increases an adversary’s propensity to assume risks. Both the Bush and Obama administrations have expressed the importance of preserving the global and regional perception of the United States as the guarantor of Persian Gulf security. Conversely, Iran has been unable or unwilling to act overtly to protect its proxies, such as during the Israeli incursion in Lebanon against Hezbollah in 2006, in response to the Israeli strike on Syria’s nuclear facilities in 2007, or during the 2011 Syrian popular rebellion.
•The Nuclear Question. How does either party’s nuclear capability affect the question of conventional-force deterrence? One of the key issues in considering this question is assessing each side’s second-strike capability, about which an enormous amount of ink was spilled over the course of the Cold War. While we have sidestepped this question to a degree in the course of this study’s assumptions, we do so as a result of the conclusion that any US deterrence strategy must take such capabilities into account to succeed. We will also consider Iran’s prospects for creating such a capability.
•The Conventional Forces Order-of-Battle Question. What are the nonnuclear military capabilities that the two parties might bring to bear in a crisis or conflict? Assessing nonnuclear military balances is inevitably an imprecise calculation, even when, as in the Cold War, there was a well-established body of knowledge not only about the Red Army order of battle but also about Soviet military doctrine and readiness. As will become apparent, assessing Iran’s nonnuclear military capacity is a more difficult task. Do the activities of Iranian or Iranian-backed special groups in Iraq count? What about Hezbollah in Lebanon? Is Assad’s Syria, at least for some purposes, a de facto Iranian proxy? The current military balance involves many more asymmetries of capability, and once again, the Cold War experience does not necessarily serve us well. Nevertheless, it is generally true that the more favorable the military balance or, more precisely, the more favorable the perception of the military balance is to the challenger, the more difficult the task of deterrence. Finally, this precept needs to be applied narrowly and precisely relative to the challenger’s object. Iran may well view itself as generally weak in regard to the United States, but it might easily regard the situation in the region as generally favorable. For example, deterring Iran from interfering in Iraq thus far has proved impossible.
•The Strategic-Culture Question. How do larger and longer-term international self-perceptions, traditions, and patterns of behavior shape the deterrence equation? The key idea behind the notion of strategic culture is that a country—or any actor on the international stage—defines its security goals and strategy in a way that reflects its political culture. Political culture is a constant that has a measurable effect on the ways in which decisions are made and wars are waged. Alastair Iain Johnston’s summary definition of strategic culture is plain: “Those who use it tend to mean that there are consistent and persistent historical patterns in the way particular states think about the use of force for political ends.”39 Conversely, two different states facing roughly similar challenges of international politics or security might well act in entirely different ways, reflecting different strategic cultures. We regard this question to be of critical importance in assessing the prospects for deterring a nuclear-armed Iran.
Assessing the Prospects for Deterrence
The United States has been practicing a loose form of deterrence against Iran for the better part of three decades, since the revolutionaries inspired by Grand Ayatollah Ruhollah Khomeini seized the US embassy in Tehran and held fifty-two diplomats hostage for 444 days. Yet the range of possible conflict points has mushroomed. What might be called the canonical military threat from Iran—the closing of the Strait of Hormuz, a chokepoint through which approximately 17 percent of the world’s crude oil passes40—remains a serious concern, as do a variety of direct Iranian threats such as regular harassment of US shipping by Iranian small boats. Further, the dangers of Iranian irregular combatants or proxies are a critical and possibly existential worry to America’s newest allies in the region: Iraq and Afghanistan. Iran’s Hezbollah proxy in Lebanon wages an ebb-and-flow war against Israel, a conflict that broke into large-scale conventional operations in summer 2006. Now the shadow of Iran’s nuclear program casts a pall from the Persian Gulf to Europe to Central and South Asia.
A central question for a strategy of deterrence is what individual leaders, groups of leaders, and Iranian institutions are the objects and targets of deterrence. Deterrence is psychological, a calculation that the perceived costs of aggression outweigh the perceived benefits. Iran’s diffuse leadership structures make the job of deterrence extremely challenging. Constant domestic power struggles within the regime make deterrence even more difficult.
Obviously, the first object of a US deterrence strategy for a nuclear Iran would be to prevent not only the regime’s use of nuclear weapons but also conventional attacks it might feel capable of executing because it possesses nuclear weapons. Nuclear proliferation from Iran to others is another concern. Even without a nuclear weapon of its own, Iran is difficult to deter. The current, de facto deterrence regime does not prevent Iran from isolated acts of military aggression or from aggression by Iranian proxies or partners. A more thorough assessment of the traditional questions of deterrence suggests the magnitude of the task.