Minimum Deterrence

July/ August 2008 |
A strong case could be made for the idea that a policy maker sane enough to be deterred in the first place is unlikely to consult force exchange ratios or find comfort in strategic superiority when contemplating a nuclear war.
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Nuclear deterrence is a rather subjective concept: How many weapons are enough to ensure deterrence? How difficult is it to achieve and maintain deterrence? How important are the technical details of a country’s nuclear forces, such as the size, configuration, and readiness, to the goal of maintaining deterrence? The answers to these questions vary across recent history and across geographic areas.

One view, I would say the dominant view in U.S. defense planning, is that deterrence can be achieved only through difficult choices, sustained with intelligent effort, and will depend very much on the technical details. This is the view expressed in Albert Wohlstetter’s 1958 Rand monograph, The Delicate Balance of Terror, which helped to shape the dominant Cold War attitudes about deterrence.

A different view is that, beyond a certain point, all of this is crazy talk, and the technical details don’t matter very much at all. The balance of terror is anything but delicate. An enemy who can be deterred, will be deterred by the prospect of a counterattack, even if it consists of only a few nuclear weapons. Beyond that minimum threshold, nuclear weapons provide little additional deterrent benefit.

This view, which is often referred to as minimum deterrence, is probably the most prevalent view regarding nuclear strategy -- outside of the small and dwindling group of people who have dedicated their lives to modeling force exchange ratios (how much of an enemy’s war-fighting capacity would survive an attack compared to how much of their own war-fighting capacity would survive) and calculating equivalent megatons. In 1960, strategist Herman Kahn, no great fan of what was then called either “minimum” or “finite” deterrence, was tempted to call it the layman’s view but resisted, because the “view is held by such a surprisingly large number of experts that it may be gratuitously insulting” to use that description.

Kahn had a point. After all, no one could call J. Robert Oppenheimer, director of the Manhattan Project, a layman. Oppenheimer perfectly expressed the logic of minimum deterrence in response to the growth in U.S. and Soviet nuclear forces in 1953 when he said, “Our twenty thousandth bomb will not in any deep strategic sense offset their two thousandth.” Oppenheimer emphasized numbers, but the argument for minimum deterrence is about more than just arsenal size. At its core, the argument for minimum deterrence has been that, despite the fine calculations of strategic planners, political leaders in particular will recoil at the terrible destructiveness of nuclear war, making the balance of terror quite robust regardless of differences in the number or type of weapons. This certainly is how policy makers tend to talk about nuclear weapons. For example, in Unarmed Forces: The Transnational Movement to End the Cold War, scholar Matthew Evangelista cites a wonderful pair of remarks from Soviet Premier Nikita Khrushchev and President Dwight D. Eisenhower that suggest both saw nuclear weapons in terms of minimum deterrence. “Missiles are not cucumbers,” Khrushchev said, “one cannot eat them, and one does not require more than a certain number in order to ward off an attack.” Eisenhower was more precise about that “certain number.” “We should develop a few of these missiles as a threat, but not 1,000 or more,” Eisenhower said. He added that if the Soviet Union and the United States could launch more than that, then “he personally would want to take off for the Argentine.”

The layman’s view, though it seemed rooted in common sense, did not survive the onslaught of bureaucratic and technical pressure for more, more, more -- more warheads, more yield, more types of delivery vehicles, and other innovations. The air force and army fought over which would control the new ballistic missile -- an argument that the air force essentially won. The air force and the navy argued about whether the United States should rely on very accurate land-based missiles or more survivable submarines. The air force pressed for missiles with better inertial guidance, the ability to place multiple warheads on each missile, and eventually mobile missiles. The navy, too, eventually sought better accuracy and nuclear weapons with larger explosive yields to stop air force officers from derisively calling navy nuclear weapons “firecrackers.” These debates played out, beginning in the late 1950s, with some military theorists arguing for a counterforce nuclear strategy -- the idea that the United States should target military assets as part of a credible war-winning strategy rather than cities as a means for deterrence. The dominant trend was clear by the end of the decade. At the end of the Eisenhower administration, U.S. nuclear forces had grown from more than 800 nuclear weapons to more than 18,000. And, despite Ike’s preference for the Pampas over thousands of missiles, the air force was pressing the incoming president, John F. Kennedy, for 1,950 new Minuteman missiles.

It is in this context that we find the first use of the phrase “minimum deterrence” in an official document, presented as an opportunity to cap the Minuteman force at significantly lower numbers than desired by the air force. Defense Secretary Robert McNamara rejected the strawman strategy, along with a first-strike force. In a 1961 memo, McNamara rejected minimum deterrence on two grounds, both of which would become the canonical arguments against the posture. First, he argued that deterrence in general might fail, and in that case, a large force might limit damage to the United States. This argument receded over time as Soviet capabilities grew and the aspirations of advocates of nuclear “victory” were reduced to “limiting” the number of Americans killed to 20 million or so.

Second, McNamara argued that if it adopted minimum deterrence, the United States would be unable to extend its nuclear umbrella to its allies. This argument endured, while damage limitation did not, and to some extent remains part of the nuclear weapons debate today. For example, when president-elect Jimmy Carter asked the Joint Chiefs of Staff for a study of a minimum deterrent posture based on 200–250 submarine-launched ballistic missiles, the request was leaked to conservative journalists Rowland Evans and Robert Novak who raised the issue of the nuclear umbrella and modestly warned that the proposal would “presage the end of democratic Western Europe.”

Carter’s experience captured, in many ways, the plight of proponents of minimum deterrence. Journalist Thomas Powers, imagining the incident, made an amusing comparison: “Proposing to the Joint Chiefs of Staff a retreat to a mere 200 nuclear weapons would be like proposing to a conference of international bankers that they solve the problem of poverty by dissolving their corporations and distributing their assets to the poor. Minimum deterrence is just plain unthinkable -- the kind of thing that leaves a room in embarrassed silence.” Minimum deterrence seemed to many, as historian Lawrence Freedman wrote in his magisterial The Evolution of Nuclear Strategy, the province of “erstwhile disarmers” who had conceded the practical case for deterrence.

Minimum deterrence was, however, more than a strawman or a calumny, taken seriously only by former disarmers and nuclear pacifists. Though not everyone liked the phrase “minimum deterrence” or agreed on the optimal posture, a strong case could be made for the idea that a policy maker sane enough to be deterred in the first place is unlikely to consult force exchange ratios or find comfort in strategic superiority when contemplating a nuclear war. After leaving office, officials from the Kennedy and Lyndon B. Johnson administrations, including McNamara and National Security Adviser McGeorge Bundy, forcefully argued this point, drawing heavily on their experience during the Cuban Missile Crisis to suggest that strategic superiority offered no comfort in October 1962.

In addition, scholars began applying the lessons of organizational theory to nuclear deterrence. If the chances that a rational leader would initiate a nuclear war were vanishingly small, then the only route to nuclear war would be inadvertent -- the possibility that large, alert nuclear forces, embedded in the day-to-day military hostility of the Cold War, might be prone to accident or error, especially in a crisis. In particular, scholars such as John Steinbruner, Bruce Blair, and Scott Sagan argued that the federal government systematically ignored the organizational dangers of the U.S. nuclear posture in an effort to wring out ever-smaller amounts of deterrence from our nuclear forces. Serious reductions in readiness, they argued, would dramatically reduce the risk of accidents or inadvertent war at little or no cost to the stability of deterrence.

As these arguments fell on deaf ears in the United States, strategic thinkers made better use of them in China and India, both of which have postures that are firmly grounded in minimalist conceptions. Chinese officials tend to eschew the word “deterrence,” yet they eagerly describe Chinese nuclear forces as minimal or, more often, limited. For many years, China has deployed a strategic monad of a hundred or so ballistic missiles, including fewer than two dozen intercontinental ballistic missiles and has pledged not to be the first to introduce nuclear weapons into a conflict. Similarly, India did not move to weaponize its deterrent after a successful nuclear test in 1974. Following a further round of nuclear tests in 1998, India deployed a small nuclear force, which Indian officials openly describe as a minimum deterrent, and it has issued a no-first-use pledge.

In the Chinese case, the idea of minimalism was integral to the process of developing nuclear weapons. In Minimum Means of Reprisal, I argue that Chinese policy makers have tended to make decisions about China’s strategic forces that suggest a widespread belief that deterrence is achieved early and with a small number of forces. Chinese advocates for strategic programs, including Marshal Nie Rongzhen, butted up against other military officials who tended to see nuclear weapons and ballistic missiles as expensive distractions from the pressing need for new ships, tanks, and airplanes. Chinese scientists were looking at broader issues. Rather than emphasizing the battlefield prowess of nuclear weapons, Chinese scientists saw their benefit for China in terms of mastering a particular set of technologies, not deploying certain forces.

In India, too, scientists were the principal advocates for the nuclear program, as George Perkovich has argued in India’s Nuclear Bomb. When Indian scientists prevailed upon policy makers to test and build nuclear weapons, their arguments emphasized national ideas of greatness more than military exigency.

Some observers have suggested that minimal deterrence is a default posture for China and India and not a considered decision, arguing that they lack the economic and technical resources for any other posture or, more condescendingly, that Chinese and Indian thinkers simply don’t understand deterrence theory. But it is quite a coincidence that China and India -- countries in which the technical community played an unusually large role in shaping the development of nuclear strategy -- maintain nuclear policies, forces, and postures similar to those preferred by Oppenheimer and many other Manhattan Project scientists. It is not simply insulting to call minimum deterrence the layman’s view, it is wrong. More often than not, it seems, scientists working from the technical realities of nuclear weapons come to the minimalist conclusion. Rather than waiting for the Chinese and Indian postures to become more like the U.S. posture, perhaps the United States should take a closer look at the minimum option.

In particular, what about Carter’s proposed force of 200–250 submarine-launched ballistic missiles? This force would translate into approximately 12 ballistic missile submarines (the United States has 14 today) and 960 nuclear warheads. Could the United States meet its vital security interests with 1,000 nuclear warheads, maintained only to retaliate against nuclear attack? There are two challenges to minimum deterrence -- one old, the other new. The old challenge is, as always, this question of allies. The George W. Bush administration broadened this debate by relying so heavily on the concepts of assurance and dissuasion. To be specific, the Bush administration has said that the United States assures its allies by maintaining numerical parity with the Russians and dissuades adversaries by maintaining deployed forces some factor (say, a factor of four) larger than the worst-case Chinese strategic force. This, along with the forward deployment of a few hundred tactical nuclear weapons in Europe, presumably keeps our friends in Germany, Japan, Turkey, and elsewhere from developing their own nuclear weapons.

Will allies feel protected by the U.S. nuclear umbrella if the United States were to have 1,000 nuclear weapons for the sole purpose of retaliating against a nuclear attack? It isn’t clear to me that nuclear weapons can or should bear the burden of maintaining the credibility of any alliance. Take Turkey, for example. If the United States and Europe get the big questions about Turkey right -- its interests in Northern Iraq and membership in the European Union -- then NATO’s nuclear posture is probably irrelevant. And if they get those things wrong, then, well, NATO’s nuclear posture is still irrelevant. Nuclear weapons are one tool, but they aren’t -- and really never have been -- a substitute for alliance diplomacy.

The new challenge is a legal one and relates to the targeting of a minimum deterrent. Would the nuclear weapons be aimed at military targets and the enemy’s weapons (in other words, a counterforce strategy) or would they be pointed toward population centers -- a countervalue strategy? In rejecting the use of the term “countervalue” in the draft Joint Doctrine on Nuclear Operations, a commenter from the Joint Staff argued, “Many operational law attorneys do not believe ‘countervalue’ targeting... is a lawful justification for employment of force, much less nuclear force.... For example, under the countervalue target philosophy, the attack on the World Trade Center Towers on 9/11 could be justified.”

This is a serious objection. If a credible deterrent cannot be based, as McNamara once argued, on taking an incredible action, then what is the appropriate target set for a minimum deterrent? One option would be to say that the United States should only target those assets that cannot be held at risk with conventional forces. Does such a target set exist? It may, perhaps in the form of hard and deeply buried targets that happen to be located in or near major urban areas. Yet, it may not; some military officials have come close to suggesting that nuclear weapons meet no unique military need. In 2007, for example, Gen. James Cartwright, then-commander of U.S. Strategic Command, testified before the House Armed Services Committee that conventional capabilities have largely replaced nuclear capabilities, with the single exception of global reach against fleeting targets. If true, then the credibility of deterrence rests very heavily on the mere existence of nuclear weapons and their inherent potential for use, rather than on plans, postures, or declaratory policies.

This is the central question of minimum deterrence, whether one is talking about the stability of deterrence, assuring allies, or credibly threatening retaliation. How much do the details matter relative to the existence of the most destructive weapons in human history? For many, talk about nuclear strategy has a surreal quality that seems disconnected, both from the realities of political life and the horror that would ensue in the event of a nuclear war. It’s this essential judgment, more than any other, that informs whether one is willing to place one’s faith in a minimum deterrent or not.