Keith Payne's The Great American Gamble is one of the most significant studies of nuclear deterrence in many years. Probing the assumptions behind conventional wisdom, and drawing upon newly declassified documents, he weaves together theory and practice to show how a particular school of thought—advocating a so-called "stable balance of terror"—came to dominate policies on such issues as nuclear deterrence, arms control, and missile defenses. Nearly two decades after the end of the Soviet Union, this school remains quite dominant. Payne reveals how its particular "expectations, definitions, norms, and force metrics" have been "so thoroughly ingrained as the acceptable parameters of U.S. strategic policy and forces that often they are unrecognized as the product of a particular set of Cold War conditions and judgments." But what made sense for those conditions and judgments may not make sense today.
The author of 16 books on strategic affairs and director of a graduate program in defense and strategic studies, Payne has served as Deputy Assistant Secretary of Defense for Forces Policy and on numerous official commissions, including those which produced the 2001 Nuclear Posture Review and the 2009 Strategic Posture Review. His study places Cold War decisions about deterrence within a theoretical context. He discusses the "stable balance of terror" school in light of one of its main proponents, Nobel-laureate economist Thomas Schelling. To Schelling, he contrasts the school informed by RAND analyst and Hudson Institute founder Herman Kahn, who favored strategic defenses and strategic superiority as a more effective and safe deterrent. Payne's purpose is not to rehash disputes of the past or to speculate on what might have been, but to burrow to the historical and theoretical roots of contemporary deterrence policy, the better to judge whether and how old assumptions and ideas fit today's circumstances.
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The "stable balance of terror" school of deterrence may be characterized as advocating roughly approximate offensive arsenals threatening both population and infrastructure, a capability of retaliation in the event of an attack, and an aversion to strategic defenses that might blunt such attacks. It was deterrence by threat of punishment—such and such nasty things will happen to you after you attack us.
Taking the "rational actor" model of modern economics and applying it to strategy, Schelling recommended a balance of terror based upon the deliberate maintenance of mutual vulnerability. The levels and types of nuclear weapons could be relatively low and simple, just rough and dirty enough to unleash an unacceptable level of destruction upon Soviet infrastructure and civilian population. Roughly similar force structures also helped make the terror "stable." If vulnerability was a condition of stability, both civil and missile defenses had to be put away. Any sort of damage limitation was counterproductive, but the model especially forbade the "defense of human resources." For all its fancy 20th-century trimmings, Schelling admitted, it was "simply a massive and modern version of an ancient institution: the exchange of hostages."
The stable-balance-of-terror model of deterrence soon came to dominate U.S. nuclear strategy. In the early 1960s, such a purely offensive form of deterrence was translated into policy under Defense Secretary Robert McNamara. Drawing upon declassified memos, Payne documents how McNamara understood that strategic defenses that could substantially reduce the possible damage of an attack were technically feasible, but he nevertheless chose to rely on mutual vulnerability because it was more cost effective and presumably more stable.
After McNamara, successive Congresses and administrations continued that policy. In 1972, Richard Nixon ratified the Anti-Ballistic Missile (ABM) Treaty, sealing mutual vulnerability with obligations under international law. The basic idea, as Henry Kissinger noted, was that "vulnerability contributed to peace, and invulnerability contributed to war."
In the 1980s, Ronald Reagan's Strategic Defense Initiative (SDI) stepped outside this framework, at least in theory. But thanks to the cancellations of programs in the early and mid-'90s, SDI never produced deployments, let alone favored strategic superiority or population defense. Thus it did not undo the vulnerability enshrined in the ABM Treaty, which Bill Clinton in 1997 called the "cornerstone of strategic stability." Arms controllers predicted with theological fervor that the sky would fall when George W. Bush withdrew from the treaty in 2002. It did not.
This school of strategic thinking manifests itself today in the advocacy of "existential deterrence," which holds that even the smallest nuclear force will be adequate to deter attacks on the United States, its forces, and its allies. Schelling suggested as few as 100 secure, nuclear-armed missiles would be enough to wreak havoc on a foreign population. In recent years, former U.S. officials from Kissinger to William Perry have signed onto a policy of nuclear reductions approaching total disarmament, an approach that has also been embraced by the Obama Administration.
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The school of deterrence associated with Herman Kahn—the road American nuclear policy did not take—added "deterrence by denial" to deterrence by punishment: not only will bad things happen to you if you attack us, but active means of defense will hinder your attack from hurting us in the first place. Instead of a balance of approximately equal terror and mutual vulnerability, Kahn favored an asymmetrical and advantageous imbalance of terror in favor of the United States and its strategic superiority.
On the one hand, superiority meant that the quality and accuracy of offensive weaponry mattered more even than their numbers. Robust, accurate offensive forces targeting military or political facilities would provide a more credible deterrent than Schelling's 100 fairly inaccurate missiles, which would deter by threatening an indiscriminate killing of civilians. But strategic advantage also implied damage limitation (air and missile defenses to deny an enemy an effective attack), and passive defenses to limit the scope of the damage. Defenses which prevented or mitigated an attack would not preclude an American retaliatory strike against an enemy, but did provide a fallback in the event of a failure of deterrence. By allowing for flexibility, defenses made a threat of retaliation more credible rather than less.
To proponents of existential deterrence, the unthinkable horror of absolute destruction seemed like a better deterrent to absolute war than defenses that would try to mitigate the damage. Missile defenses were seen as dangerous and provocative because they would encourage thinking that nuclear war was survivable—which would make the unthinkable more likely. Because Kahn's On Thermonuclear War (1960) dared to think about how best to mitigate the effects of a nuclear attack—"thinking about the unthinkable"—advocates of the stable balance of terror maligned it as an immoral defense of mass murder. Thinking about the unthinkable must itself be forbidden, since it would signal to the other side that we might not be content to remain fully vulnerable.
Today, strategic vulnerability is sacred orthodoxy to the intellectual and policy-making establishment that presides over American nuclear strategy and arms control. To them, Payne's resurrecting these old questions will seem downright heretical. But rediscovering Kahn's heterodoxy is useful to combat today's unquestioning faith in the automaticity of deterrence. Deterrence cannot be reduced to mathematics or game theory; it is profoundly psychological, and its success depends upon the contingent acts of real human beings. An effective deterrent must get into the minds of the persons who would be deterred, to get them to refrain from the action in question. Active defenses and damage limitation measures may serve as a defensive deterrent against rogue states or terrorists who do not fit the usual profile of a rational actor.
The simplicity of Schelling's elegant model made it all the more attractive to strategists and arms controllers. And perhaps it did fit the circumstances of the Cold War. But its simplicity may also make it obsolete in changed circumstances today. For while this model provides the major premise—that a rational actor would not choose the irrational—it simply assumes the minor premise, that any weapon-of-mass-destruction attack is irrational, or that there are no irrational actors who would try such an attack.
Critics will say that Payne's reconsideration of Khan's approach tries to make the world safe for nuclear weapons. But nuclear proliferation has managed to make the world less safe all by itself, and the question remains what to do about it. Of course we want to deter an attack, but what deters? The answer to this question will not always be the same in all times and all circumstances. But before one may even ask this question, one must escape the intellectual shackles of the stable-balance-of-terror theory.
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In a 1981 essay, "The Spread of Nuclear Weapons: More May be Better," international relations professor Kenneth Waltz argued that nuclear proliferation might not be such a bad thing after all. If one adopts as a categorical imperative that purely offensive deterrence is best, then such proliferation might be welcomed as a felicitous means to usher in world peace, stability, and respect among nations. But what may have then seemed a pleasant academic exercise in logic seems foolish in the face of real-life proliferation in the 21st century.
The legacy of making strategic vulnerability the "cornerstone" of security is not reassuring. Decisions made by McNamara more than four decades ago to forgo air defenses (if you're vulnerable to intercontinental ballistic missiles, why bother to defend against bombers?) were partly to blame for the blinding lack of airspace awareness on September 11, 2001. The 9/11 Commission Report dryly observed that "NORAD was not postured adequately to protect the United States."
The best defense may have been a good offense during the Cold War, but even that was a gamble. Even assuming that it paid off with respect to the Soviet Union, we should think twice before doubling down today. Arms controllers who oppose missile defenses often do so without taking seriously what it might take to deter a rogue regime armed with nuclear missiles, or even a terrorist group with a cruise missile carrying chemical or biological weapons. The threat of overwhelming retaliation after an attack might deter an attack by such actors—but it might not. The stakes of hoping that it will are pretty high. As a February 2010 Department of Defense review of missile defense policy noted,
deterrence by threat of a strong offensive response may not be effective against these states in a time of political-military crisis. Risk-taking leaders may conclude that they can engage the United States in a confrontation if they can raise the stakes high enough by demonstrating the potential to do further harm with their missiles. Thus U.S. missile defenses are critical to strengthening regional deterrence.
Active missile defenses to mitigate the effects of such an attack will not be cheap, but they may be necessary. At any rate, doubling down today on the vulnerability of classical deterrence does not seem like a very good bet.
Those who support nuclear weapon upgrades or robust missile defenses today are caricatured as hawkish Cold Warriors unwilling to face a 21st century where such thinking is more obsolete than ever. But Keith Payne shows how the shoe of obsolescence may in fact be on the other foot. Those who reflexively and dogmatically oppose missile defenses and nuclear modernization programs are locked into arcane Cold War formulae, not the other way around. Maybe thinking about the unthinkable ought to be the job of defense planners after all.