deterrence

1. The act or a means of deterring.
2. Measures taken by a state or an alliance of states to prevent hostile action by another state.

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noun

The act of preventing: determent, forestallment, obviation, preclusion, prevention. See allow/prevent.

To threaten a response to a given action in order that the perpetrator is convinced that the benefits of the action will be outweighed by the costs incurred and is thus persuaded not to act as planned. A number of ingredients must be in place for deterrence to function. First, the deterrer must have the capability to carry out the threat which has been made. Second, the threatened response must seem credible to the potential perpetrator. Credibility requires that the deterrer has, as well as the capability, the will to carry out the threat, and that this can be communicated to and understood by the potential perpetrator. Deterrence is therefore a relationship, and one in which both sides employ a broadly compatible rational framework and discourse.

Deterrence is common to many human relationships and situations, ranging from the upbringing of children to society's attempts to control crime: however, the term has become best known as a feature of military strategy. The basic ingredients remain: a potential aggressor's cost-benefit calculation might be influenced by the threat of a punitive response, or by the realization that the defender's preparations are so advanced and effective that the costs of carrying out the aggression would be too great. Throughout human history, when an aggressor has taken stock and decided not to proceed, it may be that deterrence played a part. The difficulty with this assumption, and with deterrence thinking generally, is that it will always be difficult to isolate the reasons for a war not taking place.

There has been no shortage of war in human history. In some cases (though by no means all), clues can be found which help explain why and how deterrence can fail. If the deterrer's military capability and his will to use it are not credible, or if the communication between adversaries is flawed, then the deterrent threat will not be convincing. Even when deterrence has none of these flaws, an aggressor may simply refuse to be deterred, calculating that, although the military balance is not in his favour, his own brilliant generalship (perhaps with the addition—in the case of such as Cromwell, Jackson, and Wingate—of Divine Providence) will save the day. It is important to note that deterrence generally survived such challenges and remained a valid, respectable, and rational policy option, albeit one which could be improved next time around. But with the invention of atomic and nuclear weapons and the onset of the Cold War, military deterrence became extremely elaborate. In the nuclear world deterrence became not merely an element of defence and military strategy, but its defining feature. Deterrence could no longer be either challenged or ignored, no matter how brilliant the general. Rather than one among several options available to political and military leaders, deterrence became the end itself. However, deterrence could not be analysed too closely, for fear of revealing its fragility. It could not fail, but neither could it be tested. In his Strategy in the Missile Age (1959), Bernard Brodie pointed to the difficulties of deterrence under the nuclear shadow: ‘We expect the system to be always ready to spring while going permanently unused.’

After their use against Japan in August 1945, there was a tendency to see atomic weapons as super-bombs, and as a means to extend and amplify existing doctrines of strategic air power. For the first few post-war years, the USA enjoyed an atomic monopoly and could make such threats without undue reflection and with impunity. As the Cold War advanced, nuclear weapons were seen to offer other advantages. They offered more ‘bang for the buck’ than an expensive conventional-force posture and could offset weaknesses in conventional defences, particularly at a time when the conventional strength of the USSR was thought to have remained overwhelming while the USA and its European allies had demobilized rapidly after the war.

The communist coup in Czechoslovakia in February 1948, the Soviet blockade of West Berlin from June 1948 to May 1949, and the outbreak of the Korean war in June 1950 challenged any suggestion that the mere possession of a limited atomic weapon arsenal would prevent all Soviet aggression and communist adventurism. But the response of the USA and its allies was to place more, rather than less, emphasis on the deterrent value of nuclear weapons. This policy was manifested in two ways. The first, known as the policy of ‘massive retaliation’ was embodied in a January 1954 speech by John Foster Dulles, US Secretary of State, and in the MC (Military Committee) 48 alliance strategy adopted by NATO in December 1954. With massive retaliation, the USA and its allies threatened an overwhelming nuclear response to any Soviet aggression. The second strand to the pro-nuclear bias was the ‘New Look’ policy adopted by the US National Security Council in October 1953 and thereafter by NATO. New Look placed greater reliance on nuclear forces—tactical as well as strategic—in another attempt to compensate relatively cheaply for perceived weaknesses in the West's conventional defences.

But just as the era of US atomic monopoly was short-lived, so the period when the West could enjoy atomic and nuclear superiority was to come to an end. The USSR tested its first atomic bomb in August 1949 and its first hydrogen bomb in August 1953, just nine months after the first American H-bomb test. The next step was to produce a ‘deliverable’ H-bomb, achieved by the USA in March 1954 and by the USSR in November 1955. In August 1957 the USSR came first in the race to test an intercontinental ballistic missile, beating the USA by almost five months, and the launch of Sputnik, the first space satellite in October 1957 removed for ever any notion of Soviet strategic inferiority. Both sides were now on the verge of nuclear ‘parity’.

Beneath the ‘Missile Gap’ panic which coursed through the US administration in the late 1950s, lay the realization that a major shift in Cold War politics had taken place. In the era of the Wohlstetter ‘balance of terror’, nuclear weapons could no longer be seen simply as super-bombs, but would have to become instruments of stable diplomacy. The significance of the events of the late 1950s was that the equalization of capabilities brought with it the equalization of vulnerability. Deterrence would now become increasingly more complex. At its core remained the notion of a relationship between adversaries, but the relationship would be more delicate and volatile, and the costs of breakdown higher than ever before. With each side vulnerable to a nuclear strike by the other, nuclear weapons no longer conferred a simple military advantage, and their use could not be threatened unilaterally to deter general aggression by a nuclear-capable opponent. Indeed, rather than deter action by the other side, the object of deterrence shifted to the prevention of nuclear use, with each side deterring itself as much as its adversary.

The pursuit of a stable relationship between the superpowers saw the development of a new doctrine of nuclear deterrence in the 1960s: ‘mutually assured destruction’ (MAD). At the heart of the new doctrine lay the ability for each side to inflict ‘unacceptable damage’ on the other in a retaliatory strike. This in turn required each side to possess a guaranteed second-strike capability, one which could survive the opponent's massive, and possibly unanticipated, first strike. Various devices were considered to guarantee such a capability: the ‘hardening’ of missile silos to protect against first strike and the use of a ‘triad’ system, whereby retaliatory forces would be deployed in missiles, aircraft, and submarines, with the probability that at least one element of the triad would survive. Other ideas in the same vein included the notion of ‘Launch on Warning’ or ‘Launch under Attack’, which would automate the response.

MAD had other requirements, not the least of which was the need for ‘mutual vulnerability’: if either side were able to defend itself against attack, then it might not be deterred against making its own first strike and any stability in the relationship would vanish. It was this realization which brought both sides to ban ballistic missile defence systems in the Anti-Ballistic Missile Treaty of 1972. MAD also emphasized the need for arms control, to prevent an unstable arms race (the Strategic Arms Limitation Talks began in 1969), and good communications between the adversaries.

MAD had a number of credibility problems. If MAD were geared to preventing a massive strategic nuclear attack, what use could the strategic triad be in the arguably more likely event of a sub-strategic nuclear, or even conventional, aggression by the USSR and Warsaw Pact? How could MAD compensate for the West's continuing conventional inferiority in Europe? Could MAD credibly be extended to cover US allies in Europe; would the loss of Hamburg to East German ground forces really be sufficient reason to begin an apocalyptic nuclear exchange with the USSR? These dilemmas prompted the development of two new ideas. The first was the doctrine of ‘flexible response’, adopted by NATO in 1967. At the heart of flexible response was the claim that aggression should be met at the appropriate level if the response (and therefore the deterrent) was to be credible. Thus, a limited conventional incursion on the central front in Europe should be met in kind, as should a limited or ‘theatre’ nuclear attack, and so on all the way up to a full-scale strategic assault. And as the aggressor increased the stakes, he was to be matched at every step. Deterrence, therefore, was to be ‘graduated’, and the fact that a ‘ladder of escalation’ existed from tactical up to strategic should mean that an aggressor would think twice about embarking upon any adventurism in the first place, even at the lowest level.

The second idea entailed a return to earlier thinking about the use of nuclear weapons as tools of war rather than of diplomacy. If nuclear weapons only had value in the context of MAD, then in a sense they had no practical application. In the attempt to rehabilitate nuclear weapons as weapons of defence against aggression, ‘Limited Nuclear Options’ were introduced into the deterrence lexicon. Among the nuclear ‘war-fighting’ options considered were an attack on the opponent's leadership and administration known as ‘decapitation’, attacks on the opponent's nuclear arsenal known as ‘counterforce’, and the idea of one-shot demonstration attacks against key industrial or military centres. The prospect of nuclear war-fighting attracted a great deal of criticism. In the USA, the Physicians for Social Responsibility organization described the idea thus: ‘Planning on limited nuclear war is like planning to be a little bit pregnant.’

There were many other criticisms of MAD, and indeed of the whole edifice of nuclear deterrence. In the view of the USSR, deterrence was no more than rhetoric, behind which the USA had in reality not departed from its pre-parity thinking: nuclear weapons were valued not for their defensive qualities, but as a means to enhance military capability and ultimately defeat the USSR. The launch of Ronald Reagan's SDI in 1983, whereby the USA would be made invulnerable to a Soviet attack, only fuelled the Soviet view that the USA was seeking to break out of the strategic balance and win an overwhelming advantage. There was a deeper concern about the rationality, not just of the actors in the process, but of deterrence as a whole. Deterrence relied upon bluff. But if the bluff were called and a massive first strike launched by one side against the other, how could it be said to be rational for the victim to launch a retaliatory second strike (assuming it still could), where there could be no victory and where the result might be a counter-retaliation which would only, in Churchill's words, ‘make the rubble bounce’? There was also, finally, an important debate about the moral qualities of deterrence. The prevention of nuclear war could only be seen to be a moral good. But by the same token, the death of millions of non-combatants could only be seen to be morally reprehensible. If, to achieve the first, it is necessary to threaten credibly (and therefore with real intent) to carry out the second, how could deterrence be morally justifiable?

As the Cold War came to an end, the nuclear deterrence debate became less urgent, but at the same time more diffuse and challenging in other ways. Nuclear powers could not bring themselves to destroy their nuclear stockpiles, although large-scale reductions were made, with more in prospect. This begged the question: what use is even a reduced nuclear capability when there is no clear, nuclear-capable adversarial relationship? Does a nuclear arsenal constitute a ‘deterrent in being’, ready to be deployed against any threat, large or small, from any direction? Now that there is no massive conventional inferiority for which to compensate, should nuclear powers in NATO declare a policy of ‘no first use’, whereby nuclear weapons would become an insurance policy rather than a tool of diplomacy, and much less still a weapon of war? And finally, as the number of nuclear-capable states increases through proliferation of technology and expertise, is it naïve to expect the ideas and mechanisms of mutual deterrence to take hold in the same places and at the same rate?

— Paul Cornish

is an exercise in coercion: it involves the use of threats and/or promises to dissuade an adversary from undertaking some action it might otherwise have taken. In political science terms, one entity, A, is said to have deterred another entity, B, if B, influenced by A's explicit or implicit threats or promises, chooses to refrain from certain activities. From A's perspective, deterrence represents an effort to achieve A's goal of preserving some aspect of the status quo by obtaining B's compliance, rather than by physically preventing an alteration in that status quo. From B's perspective, deterrence represents A's deliberate manipulation of B's calculation of costs and benefits to make acceptance of the status quo more attractive than challenging it.

For deterrence to operate, two conditions must exist. First, A must possess an effective coercive strategy—some combination of negative and positive sanctions large enough to shift B's evaluation of the desirability of a particular action. Negative sanctions for noncompliance may be of three sorts: denial of benefits; retaliation; or punishment. Second, A must be able credibly to commit itself to carrying out its effective coercive strategy. Because imposing negative or positive sanctions is unlikely to be cost‐free for A, A's capacity credibly to commit itself may be problematic. Credible commitment to threats and promises can be established in three ways: by taking steps, ex ante, to ensure that the costs of failing to carry out threats and promises exceed the costs of carrying them out; by arranging for the threats and promises to be carried out automatically (as in “Dr. Strangelove's” fictional doomsday machine); or by ensuring, ex ante, that decisions to execute sanctions will be made irrationally, without due attention to costs and benefits.

Though both are exercises in coercion, deterrence differs from compellence in what A demands of B. In deterrence, A seeks to convince B not to undertake particular actions. In compellence, A seeks to force B to undertake particular actions. The distinction is between coercion aimed at preserving the status quo and coercion aimed at changing it. Deterrence is likely to be easier to accomplish than compellence because deterrence does not involve a deadline for action and is less likely to involve a visible and humiliating act of compliance, and because, whereas deterrence simply maintains the status quo, in compellence it is unclear where A's demands will end once B begins to make concessions.

Deterrence and compellence both involve coercive uses of power by A to achieve its goals indirectly, by obtaining B's compliance. They differ from direct uses of power aimed at achieving A's desired outcome regardless of B's behavior. This difference yields the distinction between deterrence and defense. Deterrence aims to reduce or eliminate B's interest in undertaking certain actions, and its success rests on A's capacity credibly to commit itself to harm B. Defense aims to reduce or eliminate B's capacity to hurt A or A's interests: its success rests on A's capacity to disarm, defeat, or protect against B. A's ability to limit or eliminate B's physical capacity to impose pain on A is irrelevant to deterrence, but is the essential element of defense. Measures aimed at defense may be preemptive (that is, may involve destroying or neutralizing B's capabilities before B has an opportunity to use them); active (defeating, repulsing, or blunting B's actions); or passive (protecting items of value against the consequences of B's successful actions).

The distinction between deterrence and defense is evident in alternative Cold War strategies developed for dealing with the possibility of a Soviet nuclear attack. The Assured Destruction and Mutual Assured Destruction (MAD) doctrines enunciated by Secretary of Defense Robert S. McNamara, and the various strategies of controlled nuclear retaliation developed after the early 1960s, reflect the logic of deterrence: they acknowledged the vulnerability of American society to a Soviet attack, but aimed to protect the territory of the United States by credibly committing it to exact appropriate retribution. By contrast, active defenses like the proposed Sentinel thin area defense antiballistic missile (ABM) program of the late 1960s, or broad missile defenses like those envisioned in President Ronald Reagan's 1984 Strategic Defense Initiative (SDI), reflect the idea of defending against, rather than deterring, an attack.

Though deterrence has always coexisted with defense as an element in American military policy, the development by the end of World War II of effective long‐range airpower, missile technology, and atomic weapons simultaneously rendered defense more difficult and increased national capacity to threaten an adversary with massive suffering. Insightful observers like Bernard Brodie noted almost immediately the basic implications of these technological developments for American security policy. The Eisenhower administration's explicit incorporation of nuclear deterrence—“massive retaliation”—into U.S. defense planning in 1954 as part of its “New Look” in national security policy sharply accelerated the development of deterrence theory, principally by civilian analysts and scholars.

The early theorizing of the immediate postwar period was supplemented in the late 1950s and early 1960s by careful analyses by Brodie, Herman Kahn, William Kaufman, Klaus Knorr, Thomas Schelling, Glenn Snyder, and Albert Wohlstetter, among others, who explored the problems of achieving credible commitment, assuring “second‐strike” capability, enhancing stability in situations of mutual vulnerability, using threats of limited and controlled retaliation to make nuclear deterrence credible even while American cities remained hostage, and employing arms control to enhance crisis management and arms race stability. This theorizing provided the blueprint for American nuclear strategy and arms control policy from the mid‐1960s until the administration of Ronald Reagan. With SDI and particularly with the end of the Cold War, the focus of U.S. nuclear policy shifted increasingly from the problem of deterrence to the problems of defense against limited nuclear attacks, as well as nuclear proliferation.

[See also Arms Control and Disarmament; Game Theory; Missiles; Nuclear Weapons; Nuclear War, Prevention of Accidental; Strategy: Fundamentals; Strategy: Nuclear Warfare Strategy.]

Bibliography

• Bernard Brodie, Strategy in the Missile Age, 1959.
• Thomas C. Schelling, Arms and Influence, 1966.
• Glenn H. Snyder, Deterrence and Defense, 1961.
• Alexander L. George and Richard Smoke, Deterrence in American Foreign Policy, 1974.
• Robert Jervis, The Illogic of American Nuclear Strategy, 1984.
• Edward Rhodes, Power and MADness: The Logic of Nuclear Coercion, 1989.
• Ted Hopf, Peripheral Visions: Deterrence Theory and American Foreign Policy in the Third World, 1965–1990, 1994

n.the prevention from action by fear of the consequences. Deterrence is a state of mind brought about by the existence of a credible threat of unacceptable counteraction.

See the Introduction, Abbreviations and Pronunciation for further details.

A policy of attempting to control the behaviour of other actors by the use of threats. The deterrer tries to convince the deterree that the costs of undertaking the actions that the deterrer wishes to prevent will be substantially higher than any gain that the deterree might anticipate making from the action. Deterrence is a general principle for human behaviour, but with the deployment of nuclear weapons by states after the Second World War, it became the central theoretical idea in the sub-discipline of Strategic Studies. Nuclear weapons made it much easier to threaten very large punishments than it had ever been with conventional weapons. Nuclear weapons initially forced the adoption of deterrence as a policy for military security because there was no effective way for states to prevent some nuclear weapons from getting through if an attack was launched. The threat of a retaliatory counterstrike thus became the centrepiece of superpower military policy during the Cold War. The desire to escape from deterrence led to pursuit of defences against ballistic missiles, but the technical difficulties of this option have not yet been overcome.

Deterrence is associated with nuclear retaliation, and is sometimes used in contrast to defence. The key distinction is between strategies of denial (seeking to block an attack directly by confronting the forces making it), and strategies of retaliation (inflicting punishment, usually elsewhere than on the attacking forces). Where there is geographical contiguity, as there was between the NATO alliance and the Warsaw Pact, then denial easily became part of deterrence policy. The strategy of NATO was to confront Soviet forces with a ladder of escalation, starting with conventional defence and moving up rungs to a full-scale nuclear strike.

Although simple in conception, deterrence can be extremely complicated in practice. If two nuclear powers confront each other, each fears that a first strike by the other could disable its retaliatory forces. Under these conditions, each side must pursue a secure second strike force: one that is large enough to survive a first strike and still inflict unacceptable damage in retaliation. Fear of becoming vulnerable to a first strike (and/or a desire to attain first-strike capability) gives technology a central role in deterrence, and tends to fuel a high-intensity qualitative arms race. Deterrence theory was shot through with many debates about problems of rationality, dangers of accidental war, and dangers of uncontrollable escalation from peripheral conflicts. Because it developed largely in the context of the Cold War, deterrence theory is largely cast in terms of a two-party relationship, with much less thought having been given to the operation of deterrence logic in a multipolar system. For the United States and its allies the issue of extended deterrence became the core focus of NATO policy. Extended deterrence required the United States to give a nuclear guarantee to its allies, and the problem was how to make this threat credible once the Soviet Union acquired the ability to make nuclear strikes against North America. Maintaining credibility was seen as the central problem for American deterrence policy throughout the Cold War.

Deterrence theorists can be divided into two groups. On one side are those who think that nuclear weapons make deterrence easy. They tend to support policies of minimum deterrence, the logic being that deterrence is made effective by the appalling consequences of even small nuclear strikes. On the other side are those who think deterrence is difficult. They focus on the complexities of the escalation ladder, and the need to deter highly aggressive, risk-taking, opponents under all foreseeable contingencies. They tend to favour large and diverse nuclear force structures capable of dealing with all worst-case scenarios. Extended deterrence favoured the ‘difficult’ logic, and with the ending of the Cold War, there has been a general move towards minimum deterrence amongst the big nuclear powers. Nuclear deterrence has implications for nuclear proliferation. To the extent that the large powers rest their own security on nuclear threats, it makes it difficult for them to persuade other states that they should renounce their right to possess nuclear weapons.

— Barry Buzan

In one form or another, deterrence is a motivational force in many everyday relationships: a child learns not to misbehave for fear of being scolded by its parents; a potential criminal might decide against committing a crime for fear of being caught and punished; a nation may choose one foreign policy course over another out of fear of military or economic retaliation; or an international alliance may threaten war if any one of its members is attacked. In each case, one party has influenced the choice of another by threatening consequences that outweigh gains.

In the field of foreign policy, the threat and fear of retaliation has been a powerful force. Imperial powers have found that making an example of an enemy or lawbreaker ultimately provided a cheaper and easier method of controlling peoples than maintaining a large standing police or armed forces, conforming to the common adage that prevention is usually better than cure. To that end, Roman legions deliberately cultivated a reputation for ruthlessness to promote stability, and European imperial powers did everything they could to impress their technological and military prowess upon the peoples they commanded. But it is in the nuclear age that deterrence assumed a special significance and was refined from a mostly instinctive practice to a deliberate, if still inexact, science. Throughout the nuclear age, deterrence has been a dynamic concept propelled by technological and historical developments. In turn, the concept of deterrence came to influence those technological and historical developments.

The Theory of Deterrence

In its most basic theoretical form, deterrence is an equation involving two parties, where one party weighs the gain it may make by pursuing a course of action against the price it may pay by the retaliation of the other party. By way of illustration, it is useful to consider two nations, Nation A and Nation B, whose interests collide on a particular issue. If Nation A is known to be considering a course of action contrary to the interests of Nation B, Nation B may signal its intent to retaliate if Nation A does indeed choose that course of action. This leaves Nation A with a decision. First, it must decide whether Nation B has the capability to carry out its threat, and, second, it must decide whether Nation B has the will to carry out its threat. And the deciding factor in both of these judgments is the credibility of Nation B's capability and will to carry out the threat. If, as a result of this cost-benefit calculation, Nation A decides not to go ahead with the course of action, then deterrence has been successful; but if Nation A decides that the gains out-weigh the risk or price, and goes ahead regardless of the threat, then deterrence has failed. This example, though, provides only the barest outline sketch of how deterrence operates in the foreign policy arena.

The simplicity of the theoretical formula belies the complexity of international diplomacy in practice and critics of deterrence have focused on the relative rigidity of the formula compared to the fluidity and unpredictability of international diplomacy. Furthermore, deterrence rests heavily on certain assumptions about the parties involved and the way they will react. First, deterrence rests heavily on the belief that rationality will prevail throughout the process. Not only do the various parties have to behave in fundamentally rational ways, but each party must perceive the other as behaving in a fundamentally rational way. In practice, this leads to a complicated process of perception and counterperception as policymakers and intelligence bodies from each nation estimate and try to influence what the other is thinking.

Critics of deterrence rightly point out that the decisions of political leaders often do not fall into neatly explainable categories and that however carefully the deterrence situation may be controlled, ultimately the decision is a subjective one. In foreign affairs as in everyday life, behavior in deterrence situations is based on instinct as well as reason and this instinctive element can never be confidently discounted. Moreover, the way both parties view the situation can be influenced qualitatively by any number of factors, including irrationality, misperception, poor judgment, or even just wishful thinking. In short, what may seem an unacceptable price to one person or under some circumstances could well be judged by another under different circumstances to be acceptable. Moreover, since history is filled with events that were quite simply unpredictable, it is clearly difficult to account with any certainty for the myriad of accidents, mistakes, and emotions that may play a part in a decision. At best, employing deterrence is an approximation, but in the thermonuclear age, with weapons capable of global annihilation, the stakes are higher than ever before.

Because deterrence is very much in the eye of the beholder, and actual intentions and capabilities are less important than the other side's estimate of those intentions and capabilities, the process of communicating and interpreting information is crucial. Known as signaling, this two-way discourse is open to a wide range of possible scenarios. One involves explicit communications, including public speeches and classified diplomatic correspondence. Another is implicit measures such as partial mobilization or the placing of forces on alert or more subtle measures designed to be detected by foreign intelligence bodies. Ideally, each method is designed to exploit the complex interplay of perceptions and counterperceptions.

Sometimes deterrence fails. Often in the history of international affairs the cost-benefit calculation has led to an unexpected result. In 1904 Russia ignored Japanese warnings that its policies would lead to retaliation, resulting ultimately in the Russo-Japanese War. In 1914 the Central Powers recognized that their policies risked drawing the Entente into war in Europe, but continued regardless. During World War II, Nazi Germany persisted with U-boat attacks on American transatlantic merchant shipping despite President Franklin D. Roosevelt's explicit warnings that it would likely provoke U.S. retaliation. In December 1941, despite U.S. military strength, Japan calculated that its interests were best served by a surprise attack on the U.S. fleet at Pearl Harbor. In mid-1962 Soviet premier Nikita Khrushchev installed nuclear missiles in Cuba despite President John F. Kennedy's explicit warnings that doing so would provoke U.S. retaliation. And in 1991 the Middle East erupted in violence as Saddam Hussein ignored the threat of U.S. intervention should Iraq invade Kuwait.

Strategic Bombing

In diplomacy, threats that act as a deterrent have most often come in military form and have therefore implied the capability to project military power. Possessing a powerful navy gave Britain such a capability, but for much of its early history, the United States was not able to project military power and therefore made threats rarely and with questionable success. One notable deterrent effort was President James Monroe's unilateral declaration on 2 December 1823 of the independence of the Western Hemisphere, issued in order to deter Spanish intervention in Latin America and Russian expansion on to the American continent. Monroe's threat was twofold. First, he implied local military resistance if Spain tried to reestablish its colonies in Latin America or Russia expanded onto the American Northwest Coast. Second, he implied that if the European powers chose to interfere in the affairs of the Western Hemisphere then the United States would be forced to revoke its longstanding tradition of non-interference in European affairs. Ultimately, Spain did not try to reestablish its colonies, although this probably had less to do with Monroe's threats than it did with similar threats issued by Britain.

The advent of strategic bombing in the early twentieth century vastly increased the ability to project military force, and consequently led to the transformation of deterrence into its modern form. The twin technological developments of high explosives and aircraft that could deliver them to their targets made strategic bombing a decisive factor in modern warfare. It was first used in limited form in World War I in Germany's zeppelin (airship) attacks against Britain. German scientists had not only developed a way to incorporate poison gas into a bomb, thereby creating the first type of the weapons now classed as weapons of mass destruction, but had also developed a way to float zeppelins over enemy lines and drop their payloads on British cities. Although not widely recognized at the time, this ability to move beyond the confines of the battlefield and to attack an enemy's cities directly revolutionized modern warfare as offensive strategic bombing threatened to break the defensive deadlock that had evolved from tanks, machine guns, and trench warfare.

At the same time it introduced a new factor that, although intangible, was no less powerful. Like the German V-1 and V-2 rocket strikes during World War II, the German zeppelin of World War I resulted in few deaths, but the potential that the technology seemed to hold for extending the battlefront from the trenches to civilian homes captured the British public's imagination to an extent that far outweighed objective casualty counts. For the first time a military weapon was used not only for the tactical calculations of policymakers, but also to strike terror into the home front, which had become an increasingly vital component of modern warfare. The fluid variable of civilian morale suddenly became as important as military morale as the civilian population reacted to the new threat to their homes and lives. Moreover, during World War II, as strategic bombing became vastly more effective (and deadly), the industrial and economic hearts of an enemy became additional viable targets. Allied long-range bombers all but destroyed the German industrial city of Dresden, while the American firebombing of Tokyo started fires that raged out of control for days at a time. With the development of the atomic bomb, a weapon blatantly unable to discriminate between military and civilian targets, strategic bombing was taken to its extreme.

The development of the atomic bomb was the culmination of the top secret Manhattan Project, an extraordinary collaboration of international scientists headed by J. Robert Oppenheimer that was backed by vast resources provided by the U.S. government. Stringent security precluded public debate about what role the new weapon would have, but among those few who had information about the project's overall objective and progress, there was growing awareness that the new weapon would be unlike anything that had come before; it would perhaps even create "a new relationship of man to the universe," as a committee chaired by Secretary of War Henry L. Stimson put it. Such an unconventional weapon clearly required unconventional thinking. As Oppenheimer recognized, the elements of surprise and terror were as intrinsic to it as fissionable nuclei. In a top-secret report submitted to the War Department on 11 June 1945, a small committee chaired by physicist James Franck suggested that the psychological impact of the explosion might be more valuable to U.S. military objectives than the immediate physical destruction. In the hope that a demonstration of the destructive potential of the atomic bomb might be enough to compel the Japanese to surrender, the Franck Committee proposed a public demonstration in an uninhabited region.

After considering the various proposals, President Harry S. Truman concluded that a demonstration in an uninhabited region would likely be ineffective, and therefore ordered that the bomb be used against Japanese cities, a decision that has been passionately debated ever since. Some have argued that Truman's motivation was less the war in the Pacific than the impending contest with the Soviet Union and that as such it represented the opening gambit of so-called "atomic diplomacy," while others argue that the decision was not only militarily sound but necessary, and that it ultimately saved hundreds of thousands of American and Japanese lives. But whatever Truman's motives, at 8:15 A.M. on 6 August 1945, an American B-29 Superfortress long-range bomber named the Enola Gay delivered its single atomic bomb to the target of Hiroshima, the second most important military-industrial center in Japan. Upward of seventy thousand people were killed instantly in the blast. Three days later another bomb was dropped on Nagasaki, killing at least twenty thousand. In the following weeks the death counts in both cities rose as the populations succumbed to radiationrelated illnesses.

As the wire services flashed the story around the globe, journalists who had witnessed the Trinity test blast at Alamogordo, New Mexico, three weeks earlier on 16 July, were now free to write about what they had seen and help a startled world comprehend what had happened. The American public's reaction was a mixture of relief that the end of the war was in sight, satisfaction that revenge had been exacted upon the perpetrators of the Pearl Harbor attack, and a sober recognition of the responsibility the new weapon carried with it. In strategic terms, there was not yet such a thing as a U.S. atomic stockpile, despite President Truman's implication in his press statement announcing the Hiroshima bombing that atomic bombs were rolling off the production line. Had the first two atomic bombs failed to bring a Japanese surrender, some time would have passed before more were ready. Within days of the Nagasaki bombing, however, the Japanese leaders finally succumbed to the inevitable and formally surrendered to General Douglas MacArthur's forces on 2 September 1945. From that moment, the priority for U.S. military forces was not building more bombs, but going home.

As the United States demobilized in the postwar period, relations with the Soviet Union deteriorated. The coincidence of the beginning of the Cold War and the dawn of the nuclear age ensured that the history of the two would become inextricably entwined. During the early Cold War, the primary strategic contest was for Europe, and Germany in particular, but throughout the continent evidence mounted of a clash of interests and ideology. Within a few short years of the end of World War II, the U.S. government had publicly identified the Soviet Union as its primary strategic threat. And if war did break out in Europe, the Soviets had vastly more conventional forces and the geographical advantage as well. The challenge for U.S. defense planners, therefore, was to find a way to project the U.S. atomic force. Nevertheless, the planners moved slowly to devise a coherent nuclear strategy to serve foreign policy interests. Although fully recognizing that the Soviets would sooner or later develop the atomic bomb, American policymakers struggled to find a way to take advantage of the atomic monopoly. However, the American population was still weary from World War II and constrained military budgets were shrinking, so atomic development was a low priority. It was not until Dwight D. Eisenhower became president that a coherent deterrent role was found for the U.S. nuclear arsenal. But by the end of the Truman administration, defense budgets were growing rapidly, and that administration made some effort to bring military policy into the atomic age. Having recently witnessed how much sacrifice Soviet leader Joseph Stalin was willing to impose on his countrymen in the defense of the USSR, it was clear to U.S. policymakers that if war should break out between the two superpowers, the small stockpile of American atomic bombs that had been built up since Nagasaki would not guarantee victory.

In use, the atomic bomb was an offensive weapon. For the American atomic monopoly to be cast in a defensive role, that role had to be to prevent war altogether through the very threat of retaliation. Bernard Brodie, one of the first defense intellectuals to engage publicly the implications of the atomic bomb, succinctly summarized the momentous shift in military affairs that the bomb had sparked. "Thus far the chief purpose of our military establishment has been to win wars," Brodie commented in The Absolute Weapon (1946). "From now on its chief purpose must be to avert them." To that end, and recognizing that atomic weapons did not fall easily under the existing military force structure, the Truman administration in March 1946 created the Strategic Air Command (SAC) headed by General George Kenny. Adopting the motto "Peace is our profession," SAC's mission was to give the United States a long-term capability to project U.S. nuclear force anywhere on the globe. SAC's existence exemplified the paradox of deterrence strategies as summarized in the Latin adage Qui desiderat pacem, praeparet bellum (Let him who desires peace, prepare for war). Unlike the case with conventional military forces, for the remainder of its existence SAC's success would be measured not by its performance in battle, but by its never having actually to engage in combat.

The Cold War contest was ultimately a strategic one, but it was more often manifested in a series of short-term political contests. Committed to a policy of containing communist expansion, the Truman administration found itself having to rethink its assumption that atomic weapons would deter simply because they existed. By the end of 1948 there was mounting evidence that the American atomic monopoly was having little success in deterring communist political expansion through Europe; the threat of communist subversion in Greece and Turkey in 1947, the communist coup in Czechoslovakia in February 1948, and the strong communist presence during the Italian election of April 1948 all seemed to provide evidence to that effect. And in the first truly nuclear crisis of the Cold War, the Berlin blockade of 1948–1949, the Truman administration could manage only a half-hearted atomic threat that, if Stalin had pushed the matter, would likely have been revealed as a bluff. In a move with the twin objectives of temporarily bolstering the flagging British strategic bombing force and sending an atomic threat to Stalin, American B-29s were deployed in Britain at the height of the Berlin blockade crisis. But this early attempt at nuclear coercion was unconvincing. The B-29s initially sent were not modified to carry atomic bombs; furthermore, it was public knowledge that there was no procedure in place to store atomic warheads overseas. By mid-1948 even Secretary of Defense James Forrestal had to admit that American military planning, including its nuclear strategy, was "patchwork" at best. If America's national security was to realize the full potential of the atomic bomb for deterrence, a thorough rethinking would be needed.

One solution preferred by many was for the United States to exploit the window of opportunity by launching a preemptive strike against the Soviet Union. Former British prime minister Winston Churchill suggested sending Stalin an ultimatum stating that if he did not desist from his expansionist policies, U.S. planes would use atomic bombs against Soviet cities. The U.S. commander in Germany, General Lucius Clay, agreed. Other military voices in Washington lamented the wasting of an opportunity. The calls became more urgent as that window of opportunity seemed to be closing. When the Soviet Union detonated its first atomic device in August 1949, it caught the West by surprise. The mastering of the atomic process by Soviet scientists was not unexpected in a general sense, but beyond the inner sanctum of intelligence officials and defense planners, the Soviet achievement was never seriously anticipated beyond the vaguest of timetables. To make matters more alarming, two months later, in October 1949, Mao Zedong's Communist Party emerged victorious in China's civil war, a development seen in Washington as proof that Moscow's ambitions were not confined to Europe but were global.

The Thermonuclear Revolution

The twin developments of thermonuclear weapons and long-range missiles ushered in a new phase of nuclear deterrence. Now, thermonu-clear warheads hundreds or even thousands of times more powerful than atomic bombs could be attached to missiles capable of reaching other continents and destroying cities in minutes. In these circumstances, deterrence became not just a policy imperative but a necessity for the survival of the human race. It was clear that a new stage had been reached not only in the history of international affairs, but also in the history of humankind. J. Robert Oppenheimer famously likened the situation to "two scorpions in a bottle, each capable of killing the other, but only at the risk of his own life." In delivering a comprehensive evaluation of British and NATO nuclear forces to the British House of Commons in March 1955, Prime Minister Winston Churchill observed that a paradox was likely to define international affairs in the future: "After a certain point has been passed it may be said, 'The worse things get the better.' … Then it may well be that we shall by a process of sublime irony have reached a stage in this story where safety will be the sturdy child of terror, and survival the twin brother of annihilation." Begun by technological innovation, the thermonuclear revolution aroused the most basic human fears and instincts.

In view of the apparently intensifying communist threat, and particularly in light of the recent development of Soviet atomic power, Truman in late January 1950 ordered a reexamination of U.S. strategic policy. Secretary of State Dean Acheson delegated the task to the new director of the State Department's Policy Planning Staff, Paul Nitze. The result, a document known as NSC 68, was a lengthy and dramatic call to arms. Before long, the report concluded, the Soviet Union would have the capability to launch a surprise atomic attack on the United States. To deter such an attack, NSC 68 recommended a massive buildup in conventional and atomic forces and that, moreover, the United States should commit resources to developing a new type of weapon, a "super" bomb harnessing the power generated by fusing hydrogen atoms rather than splitting them. Preliminary research into such a weapon had been undertaken within the Manhattan Project by a team of scientists headed by physicist Edward Teller. But with no hope of immediate success and with military budgets shrinking in the postwar economic environment, the research was halted. Based on theoretical data, Teller predicted that a hydrogen bomb would be several hundred times more powerful than the Hiroshima bomb and capable of devastating an area hundreds of square miles, with radiation traveling much farther. NSC 68 now proposed to resume H-bomb research at a greatly accelerated rate. After heated debate over the feasibility and morality of such a weapon, Truman ordered the project to proceed.

At the height of the debate about whether to proceed with the H-bomb project, communist North Korea launched an attack on pro-Western South Korea on 25 June 1950. Truman reacted by committing U.S. troops under the auspices of the United Nations. Since the deterrent had clearly lapsed or failed, General Douglas MacArthur, commander of UN forces in the theater, and General Curtis Le May, head of SAC, both recommended revitalizing it by using atomic weapons against Communist China. Truman, however, refused to expand the war and committed the United States to a limited conflict with limited objectives, a novel mission for American military forces.

For both political parties, Korea confirmed beyond a doubt that communist forces were on the offensive and that existing U.S. strategy was inadequate to stop them. The Democratic administration reacted by embracing NSC 68 and the massive military buildup it entailed, including the development of the H-bomb. For Republicans, Korea seemed to provide ample evidence for their charge that the Truman administration's approach to national security policy was based too heavily on reaction rather than prevention and therefore was putting the United States on track for financial bankruptcy. They argued that the primary failure lay not in the logistical difficulties of projecting U.S. military force to the distant shores of the Korean Peninsula, but in the administration's failure to prevent the war in the first place. The debate reached a crescendo in the presidential election campaign of 1952, as General Dwight D. Eisenhower, the Republican candidate, and his foreign policy adviser, John Foster Dulles, launched a sustained political attack on the Truman administration's foreign policy record.

Eisenhower and Dulles promised to take a new look at American national security policy and formulate a better plan for what was clearly going to be a long struggle with the Soviet Union. Dulles declared that the United States could not afford to keep fighting expensive "brushfire" wars like Korea and that what was required instead was an economically sustainable military posture designed to deter communist aggression over the long term. Since the United States could not in all likelihood compete with the Soviet Union in amassing conventional forces, Eisenhower and Dulles contended that the best use of American resources would be to invest in the next generation of nuclear weaponry and declare the intention to react to communist aggression "where it hurts, by means of our choosing." To illustrate Eisenhower's proposed deterrent strategy to the voters, Dulles called on the analogy of municipal police forces: "We do not station armed guards at every house to stop aggressors—that would be economic suicide—but we deter potential aggressors by making it probable that if they aggress, they will lose in punishment more than they can gain by aggression." Massive retaliation, as Eisenhower's deterrent strategy came to be called, was designed to impose upon would-be aggressors a blunt choice: either to desist, or to persist with the risk of nuclear annihilation. The primary challenge for U.S. policymakers, therefore, was to make the other side believe that aggression carried a high risk of nuclear retaliation. To that end, Dulles declared that the administration would be prepared to engage in diplomatic "brinkmanship," a diplomatic policy some observers likened to the youthful, and often deadly, test of nerves known as "chicken." Eisenhower and Dulles argued that only by being ready to push the crisis to a point where the opponent backed down first would the United States be able to protect its interests. And in order to give communist leaders reason to pause, Eisenhower employed calculated ambiguity in responding to the question of whether a nuclear response would be automatic.

Once in office, Eisenhower and Dulles were confronted with the challenge of implementing the results of their promised New Look. Some of it was clearly impractical, even dangerous. Campaign promises of the political "liberation" of Eastern Europe were quickly abandoned after the June 1953 uprisings in East Germany. The deter-rence strategy proved somewhat easier, although perhaps even more dangerous. Increasing the relative emphasis on nuclear technology as opposed to maintaining large standing conventional forces allowed the administration to cut defense expenditures by about 25 percent compared to the late Truman years, leading Secretary of Defense Charles Wilson to declare proudly that the Pentagon now had "more bang for the buck."

Having adopted massive retaliation as a long-term Cold War strategy, Eisenhower and Dulles found that strategy tested in the short term by a series of crises. Nevertheless, Eisenhower threatened massive retaliation in times of crisis sparingly and deliberately. In a series of confrontations with Communist China ranging from bringing an end to the Korean War in 1953 to the Taiwan Straits crisis of 1958, Eisenhower several times threatened nuclear attack. The primary focus of U.S. foreign policy, however, remained Europe. The struggle for Germany continued to manifest itself in crises over Berlin, which in turn presented U.S. deterrence strategies with perhaps their most serious test. Given the superior strength of Soviet conventional forces in Europe and the location of West Berlin deep inside communist territory, that city was militarily indefensible. The situation was, as Senate Foreign Relations Committee chairman J. William Ful-bright put it, "a strategic nightmare." The only viable option available to the United States short of thermonuclear war was to deter the Soviets from moving against the city.

Simultaneous to these crises, the strategic balance was in a state of flux, which in turn affected thinking about deterrence. Although the Soviets had successfully tested their first atomic device as early as 1949, thoughtful observers recognized that one successful test did not make a deployable arsenal. By 1955, however, Soviet scientists had largely overcome the initial four-year lag and, particularly in the field of thermonuclear weapons, was on a par with the West. The Soviets still lagged far behind the United States both in quantity and quality of nuclear weapons, but the former's strategic arsenal was more than adequate to inflict considerable damage on the West and to play its own deterrent role. Furthermore, the accelerating arms race made it clear that the gap was narrowing. On 3 October 1952, Great Britain detonated its first atomic device on islands off the coast of Australia. Only weeks later, on 31 October, the United States detonated its first thermonuclear weapon. Less than a year after that, on 12 August 1953, the Soviet Union completed its first successful detonation of a thermonuclear device. In 1956 the first American tactical nuclear weapons were deployed in Europe. These new weapons, designed for battlefield use in localized action, came in the form of army artillery shells, each with explosive power roughly equivalent to the Hiroshima bomb.

This rapidly accelerating arms race confronted defense planners with a new question: How much was enough to deter? During the Eisenhower administration two main schools of thought defined the debate. The first held that the U.S. stockpile should consist of just enough weapons to play a deterrent role, a concept that became known as minimum deterrence. The opposing school of thought held that the United States should maintain a large and constantly growing nuclear arsenal in order to be able to engage in redundant targeting, or allocating several weapons to each target. Known as "overkill," it was this approach of building up an over-whelming nuclear force that prevailed, largely as a result of unchecked bureaucratic politics. As a result, for the remainder of the decade, the Eisenhower administration invested deeply in building up the U.S. nuclear stockpile.

On 3 August 1957 the successful Soviet test of a new type of missile, with the potential capability of reaching the continental United States from a launch-point in the USSR, augured in a new phase of deterrence. This was dramatically confirmed two months later, on 4 October 1957, when Soviet Strategic Rocket Forces used the same type of intercontinental ballistic missile (ICBM) to propel the world's first artificial satellite into space. That satellite, known as Sputnik, was in itself harmless, being little more than a nitrogen-filled aluminum sphere fitted with a rudimentary transmitter that emitted a distinctive "beep" every few seconds, but it would nevertheless have profound ramifications. For the world public, it offered a dramatic demonstration that suggested Soviet missile technology was ahead of the West's, especially when contrasted with a spate of well-publicized American test failures. The American public's fears were manifested in accusations that the Eisenhower administration had allowed first a "bomber gap" and then a "missile gap" to develop. In reality, neither gap existed, but the administration's critics made considerable political mileage of the issue. For deterrence theorists and practitioners, Sputnik also demonstrated that the mainland United States was for the first time vulnerable to direct missile attack, potentially opening a window of vulnerability that introduced new challenges to the viability of massive retaliation as a deterrent strategy. In response to Sputnik, the American government put new emphasis on missile technology and the space race. By the late 1950s U.S. intermediate-range ballistic missiles (IRBMs) and medium-range ballistic missiles (MRBMs) were based in Turkey and Italy, aimed at targets in the Soviet Union. In 1959 the first generation of American ICBMs, Atlas D missiles with a range of 7,500 miles, were deployed in California. The following year the Polaris submarine-launched ballistic missiles (SLBMs), the final leg of what became known as the U.S. nuclear triad, were added to the U.S. arsenal to complement the strategic bomber and missile forces. By the early 1960s the Corona intelligence satellite program was sending back its first photographs of Soviet military installations, promising a quantum leap in the collection of military intelligence. Meanwhile, development continued of the massive Saturn V rockets that, by the end of the 1960s, would finally shatter any concept of safety in geography by propelling Americans to the moon.

Once again, technological developments introduced new challenges for deterrence strategy. Since missiles reduced to minutes the time available to respond to a nuclear strike, then conceivably the side that struck first would have an advantage if it could neutralize the enemy's retaliatory capability in that strike. Accordingly, the Eisenhower administration implemented new procedures to protect its retaliatory capability. Beginning in 1952, SAC's primary strike forces were on twenty-four-hour alert to guard against surprise attack and so-called fail-safe procedures had been implemented. In highly classified Chrome Dome missions, B-52 Stratofortress bombers flew to within striking distance of enemy targets and waited for a signal to proceed. If no signal came, the planes returned to base. The procedures were designed partly to improve the response time of the nuclear strike force, but more importantly to ensure that the strike force could not be destroyed in Soviet first-strike attacks on airfields. Scattered and airborne, the strike force was less vulnerable. The same principle was also applied to command and control procedures. To reduce the risk that a Soviet first strike on a few central underground command centers might disable the entire U.S. nuclear strike force—possibly an incentive for a Soviet preemptive first strike—a fleet of air force planes were specially outfitted with command and communications equipment to be able to take control of the American nuclear arsenal in the event the central underground command center was destroyed or disabled. From 3 February 1961 through 24 July 1990, a Looking Glass plane was in the air at all times. Protected by mobility, these Looking Glass missions, along with the Chrome Dome missions, became key elements of the U.S. deterrent in the missile age by protecting America's second-strike capability.

Massive Retaliation Questioned

From the mid-1950s, criticism of massive retaliation became increasingly vocal. As Eisenhower well knew, the most challenging aspect of implementing massive retaliation was that it required a leap of faith on the part of the adversary that the United States would respond to localized and small-scale aggression by launching a nuclear strike, a reaction that was increasingly akin to suicide because of the rapid advances the Soviets were making in nuclear technology. As a consequence, there were a growing number of calls for the United States and NATO to bridge that leap of faith by modifying the strategy of massive retaliation to what retired British Rear Admiral Sir Anthony W. Buzzard called "graduated deter-rence." Only by being capable of responding in proportion to the threat, critics of massive retaliation argued, would nuclear threats become credible. Implicit here was a distinction between the tactical and strategic use of nuclear weapons, a distinction that massive retaliation explicitly disavowed. In 1957 Harvard professor Henry Kissinger elaborated on this argument by calling for increased investment in tactical nuclear weapons and acceptance of the possibility of limited nuclear war.

The observations of Buzzard and Kissinger were part of a trend toward public debate over nuclear policy. The increasing frequency of nuclear crises in the late 1950s and early 1960s and the growing absurdity of both superpowers' nuclear postures led to increased public concern with nuclear policy. For the first decade of the nuclear age, the American public had for the most part treated nuclear policy as "something best left to the experts," but by the end of the 1950s nuclear strategy had become a topic of public debate led by a cadre of increasingly visible professional strategists. Often civilians associated with think tanks such as the RAND Corporation, these professional strategists began to assume a new place in the U.S. military hierarchy and, in turn, in the public imagination. Scientists like Robert Oppenheimer, Edward Teller, and Werner von Braun had all become national figures through their contributions to the technology of the nuclear age, and by the late 1950s civilian professional strategists like Bernard Brodie, Henry Kissinger, Albert Wohlstetter, and Herman Kahn were becoming just as famous for their theorizing about how to use that technology. Although their fame most often came in the form of notoriety for their ability to discuss the absurdity of nuclear war in cold, calculating terms, they were nevertheless crucial for fueling the public debate. In the absence of hard evidence concerning Soviet decision making, these strategists were forced to form judgments about nuclear war without having any experience to draw on; thus, they substituted deductive hypotheses derived from the fields of political science, psychology, and economics for inductive historical experience. In a series of books, the most well-known of which is On Thermonuclear War (1960), Kahn challenged policy-makers and the general public to get beyond what he called "ostrichlike behavior" and to "think the unthinkable." His central point, as he put it in Thinking the Unthinkable (1962), was that "thermonuclear war may seem unthinkable, impossible, insane, hideous, or highly unlikely, but it is not impossible."

The presidential election of 1960 further propelled the public debate on deterrence. Since Buzzard's call for "graduated deterrence" in 1956, Eisenhower's political opponents had adopted the strategy under a revised name: flexible response. Maxwell Taylor, the army chief of staff in the Eisenhower administration, had for some time been a voice of dissent on massive retaliation and had expressed his concerns in his book The Uncertain Trumpet (1960), in which he called for a reprioritizing of U.S. defense spending to place more emphasis on the ability to control the escalation of crises. When John F. Kennedy was nominated as the Democratic Party's presidential nominee, he quickly adopted flexible response as the basis of his military program.

The Kennedy administration thus came to office basing much of its military program on a political refutation of the Eisenhower administration's strategy of massive retaliation. Despite campaign promises to institute ways to control escalation and thereby make crises "safer," the Kennedy administration quickly assumed an aura of being in perpetual emergency. From the failed invasion of Cuba in April 1961, the renewed Berlin crisis just months later, and the civil rights crisis at the University of Mississippi in the fall of 1962, it appeared to many that the administration was careening from crisis to crisis. The first practical test of flexible response came in the summer of 1961, when Soviet premier Nikita Khrushchev revived his ultimatum to end Western rights in West Berlin and thereby once again provided U.S. deterrence strategy with perhaps its most difficult challenge. With the crisis brewing, and concerned that he had undermined his own credibility through the Bay of Pigs imbroglio a few months earlier, Kennedy responded with a massive buildup of conventional forces in Europe in order, in his words, "to have a wider choice than humiliation or all-out nuclear action." At the same time, he reaffirmed NATO's nuclear guarantee to the city. In turn, Khrushchev quietly lifted his deadline, as he had two years earlier.

Of all the crises confronted during Kennedy's short presidency, the Cuban missile crisis proved the most dangerous, with the United States and the Soviet Union coming closer to the brink of nuclear war than ever before or since. When Khrushchev decided to deploy Soviet MRBMs, IRBMs, tactical nuclear weapons, and nuclear-capable medium-range bombers secretly in Cuba, where they would be positioned to strike most of the continental United States within minutes, his reasoning was to bolster the Soviet deterrent. Whether he wanted to use this deterrent in an offensive or defensive role has been debated by historians ever since. Once the deployments were discovered, Kennedy responded to the challenge by implementing a naval blockade of the island and threatening military action if the missiles and bombers were not removed. After a weeklong standoff, during which SAC's forces went on airborne alert, Khrushchev agreed to remove the missiles and a month later agreed to remove the bombers.

The crisis was resolved peacefully, but those who had witnessed the secret negotiations and the classified near misses had seen all too clearly how command and control might break down under crisis conditions. On the one hand, the resolution of the Cuban missile crisis without global destruction seemed to enhance the credibility of the deterrent on both sides. On the other hand, the missile crisis demonstrated that brinkmanship and ambiguity were simply too dangerous. Consequently, the crisis accelerated the momentum toward East-West détente. Formal negotiations to limit nuclear testing, which had been under way since 1958, finally bore fruit on 5 August 1963 in the form of the Limited Test Ban Treaty that effectively imposed mutual restraint on large-scale, above-ground nuclear weapons tests. And to reduce the risk of miscalculation and misinterpretation in a crisis, a communications hotline was established between the White House and the Kremlin.

Mutual Assured Destruction (MAD)

Paradoxically, however, one interpretation of the missile crisis held that the decisive factor in its resolution had been America's nuclear superiority—that if the American nuclear arsenal had not been more powerful than the Soviet arsenal, the crisis might have turned out differently. Both sides subscribed to this interpretation at least in part, which led to a new round in the arms race just as both sides were moving closer to agreements on nuclear testing. During the mid-and late 1960s, the Soviet Union expanded its military expenditures so that by the end of the decade, Soviet Strategic Rocket Forces had a new generation of even more powerful ICBMs at their disposal. At the same time, the administration of President Lyndon B. Johnson abandoned the idea of seeking an overwhelming nuclear superiority and settled upon a new measure of nuclear striking power called "sufficiency." As defined by the administration it meant having the ability to survive a Soviet first strike with enough forces intact to retaliate with a devastating second strike. To do so, the emphasis would be placed on a better balanced triad structure of U.S. nuclear forces, consisting of missile, air, and naval strategic forces, together leading to the power to "assure destruction" to an adversary without engaging in a destabilizing arms race. Secretary of Defense Robert S. McNamara argued that such a structure was both cost effective and stable, and it was retained as the structure of the U.S. nuclear force until the end of the Cold War.

By the beginning of the 1970s, the nuclear forces of the Soviet Union and the United States were at relative parity. In terms of sheer explosive power the USSR had surpassed the United States and was in the process of developing weapons with even larger payloads and greater accuracy, but the United States retained the technological lead. With this parity came new challenges to deterrence theory. No longer did one side have a preponderance of strategic power, and it appeared doubtful that even a preemptive first strike would hold the advantage, since it was increasingly clear that neither side would survive a nuclear exchange without casualties measured in the millions. American policymakers quickly found, however, that the promise of mutual destruction in the bipolar contest with the Soviet Union was frustratingly ineffective in conflicts such as Vietnam, which fell outside of the strictly defined U.S.–USSR relationship.

Mutual assured destruction (MAD) lay at the heart of the Strategic Arms Limitation Talks (SALT) that began in Helsinki, Finland, in November 1969. The objective of the talks was not to reduce the arsenals of either side but rather to negotiate limits on future growth of those arsenals precisely to preserve mutual vulnerability. Two technological developments of the late 1960s threatened to destabilize the nuclear status quo: antiballistic missile (ABM) systems and the development of multiple, independently targetable, reentry vehicles (MIRVs) technology. ABM systems, as they were conceived at the time, were designed to protect cities from incoming missiles. Both the United States and the Soviet Union had developed first-generation ABM systems that could in theory, if not yet in practice, offer protection against first strikes. Partly to overcome such an advantage, both sides had invested considerable resources in developing the technology of MIRVs, a system whereby one missile could deliver several warheads to independent targets. Although these new technologies were designed to cancel each other out, in truth they threatened to destabilize the mutual destruction deterrent and spark off a new arms race, a race that would not only be dangerous, but expensive. The SALT process, therefore, was designed to limit these technologies and keep each side vulnerable to attack by the other.

With strategic nuclear war finally recognized as unwinnable, President Richard M. Nixon ordered Secretary of Defense James Schlesinger to review the military posture of the United States in light of recent technology. The result, known as the Schlesinger Doctrine, was essentially a refinement of flexible response, designed to balance Soviet bloc capabilities by threatening retaliation commensurate with the threat. Specifically, it enhanced the role of tactical nuclear weapons in a three-layered defense structure: conventional forces for conventional threats; tactical nuclear forces to counter tactical nuclear threats; and strategic nuclear forces to counter strategic threats. In essence, the Schlesinger Doctrine embraced what Henry Kissinger had proposed in the late 1950s: that a limited nuclear war was possible and was a desirable capability to have.

Despite President Jimmy Carter's efforts to further détente and continue the focus on nuclear sufficiency rather than superiority, the international and domestic political environments of the late 1970s actually pressured the administration to increase military spending drastically. During the presidential election campaign of 1980, the Republican candidate Ronald Reagan seized upon accusations made by prominent groups such as the Committee on the Present Danger, headed by Eugene Rostow and Paul Nitze, to accuse the Carter administration of allowing a window of vulnerability to open, claiming that détente had allowed the Soviets to gain a dangerous lead in the arms race to the point that even the hardened-silo Minuteman forces, the mainstay of the U.S. strategic missile force, were vulnerable to high-yield Soviet missiles. Reagan promised not only to neutralize that gap, but also to restore American military superiority and, to that end, deliberately strove to upset the balance of terror by focusing on defense rather than deterrence. The shift had important ramifications for the Cold War. Reagan reauthorized the development of the B-1 bomber and the next generation of highly accurate and MIRV-equipped Peacekeeper missiles to replace the aging Minuteman forces. He also authorized development of a controversial radiationenhanced weapon, the neutron bomb, which killed living matter but left nonliving matter relatively unscathed. At the same time, Reagan endorsed the recommendations of a high-level commission chaired by Brent Scowcroft calling for an evolution toward small, single-warhead ICBMs backed up by Peacekeeper missiles.

In 1983 President Reagan ordered a large-scale scientific and military project to examine the feasibility of a new generation of ABM defenses. Officially labeled the Strategic Defense Initiative (SDI), but more commonly known as Star Wars after the popular science-fiction movie, the objective was to develop a multilayered shield capable of stopping thousands of incoming ballistic missiles. In theory, lasers mounted on satellites, electromagnetic guns, and charged particle beam weapons would be used to shoot down incoming ballistic missiles anywhere from boost phase (soon after launch) to reentry (final descent to target). In championing the project, Edward Teller, the reputed "father of the H-bomb," made a dramatic and controversial return to the public debate of deterrence. Not only was the technology unproven, but it quickly became apparent that the price tag of such a system was almost impossible to predict and entirely impossible to pay. Not surprisingly, the Soviet Union reacted angrily to what seemed a blatant disavowal of the 1972 SALT Treaty. Nevertheless, Reagan ordered the project to proceed. For the remainder of the 1980s, the Reagan administration struggled to find a way to make SDI a reality while at the same time continuing to pursue meaningful arms reduction.

After the Cold War

With the end of the Cold War and the disintegration of the USSR from 1989 to 1991, the bipolar balance of terror suddenly collapsed, and it became clear that the Soviet nuclear strength had been disguising severe internal weakness. Almost overnight, it seemed, the international environment had changed almost beyond recognition. But the U.S. and NATO defense postures, built up so carefully and at such expense over the previous half century, could not change so quickly; U.S. foreign and military policies relied heavily on deterrence and they would need time to adjust. For deterrence, this had profound and often unforeseen challenges.

As it happened, cutting forces was relatively straightforward; the more difficult stage of adapting military strategy to the post–Cold War situation was that of reducing reliance on nuclear weapons. The problem was approached in two steps. First, the progress made over the previous decade in arms reduction was to be consolidated and advanced. The United States and Russia were committed to deep cuts in their strategic arsenals; under the terms of the START (Strategic Arms Reduction Talks) II treaty, those arsenals would be reduced to approximately one-third their size at the height of the Cold War, and both sides would eliminate the most destabilizing of the first-strike weapons, the MIRVed ICBMs. NATO, still formally committed to the defense posture of flexible response, concluded that it had to move away from a forward defense posture and that, accordingly, in the post–Warsaw Pact strategic landscape, substrategic, short-range nuclear weapons—that is, tactical IRBMs and MRBMs—no longer had a viable deterrent role. Consequently, at the NATO heads of state meeting in London on 5–6 July 1990, NATO committed itself to eliminating all nuclear artillery shells in Europe. At the same time NATO declared that it now regarded nuclear forces as "truly weapons of last resort." Simultaneously, negotiations were under way for what became the Conventional Forces in Europe (CFE) Treaty, which provided for drastic cuts in both NATO and Warsaw Pact conventional forces stationed in Central Europe. In September 1991, President George H. W. Bush declared that the forward deployment of tactical nuclear forces was no longer a useful part of the U.S. deterrent and that he was therefore ordering the removal of all tactical nuclear weapons from the U.S. Navy. Never fully abandoning Reagan's dream of an impenetrable shield against incoming missiles, the Bush administration quietly proceeded with a scaled-down version of SDI.

If the end of the Cold War drastically reduced the likelihood of strategic nuclear war, it nevertheless increased the risk of a small-scale nuclear exchange, mainly because of the growing problem of nuclear proliferation. In an effort to bring nuclear policy up to date and to confront head-on the problem that nuclear proliferation and the equalization of power that it created might one day work against the United States, the Clinton administration in late 1993 announced that it planned to redefine "deterrence." No longer would the emphasis be on preventing the use of weapons of mass destruction, since that risk had declined markedly; instead, the focus would be on preventing the acquisition of those weapons. The announcement was followed up in September of the following year with a formal replacement of the MAD doctrine with "mutual assured safety" (MAS), a long-term program designed primarily to make Russia's military reductions irreversible by reducing not only the number of weapons themselves but also reducing the technological and industrial infrastructures needed for nuclear weapons development. Through economic incentives and technological aid, steps were taken to dismantle what Soviet leader Mikhail Gorbachev called the "infrastructure of fear." By November 1997, in the first formal presidential directive on the actual employment of nuclear weapons since the Carter administration, President Clinton formally abandoned the Cold War tenet that the U.S. military forces must be prepared to fight a protracted nuclear war. Nuclear weapons would still play an important deterrent role, but the emphasis on them would be reduced in keeping with the changing nature of the threats in the post–Cold War international environment.

While the role of nuclear weapons in the U.S. military posture was reducing, the role of conventional weapons was increasing. Confronting crises in the Balkans and the Middle East, the United States and its allies demonstrated that they could now project conventional military force with great effectiveness. Exploiting the so-called "revolution in military affairs" of superior intelligence information coupled with technologically advanced conventional weapons, the United States and NATO were able to strike with overwhelming conventional military force in a precise and controlled manner, leading to successful combat in both regions while suffering few casualties. Such capability, demonstrated convincingly and publicly, became an important part of U.S. efforts to confront and deter what the defense community called "asymmetrical threats," or threats from rogue nations or terrorist organizations.

The role played by nuclear weapons and the deterrence strategies they bred since 1945 is a controversial issue. Many historians have argued that the very existence of nuclear weapons deterred the outbreak of another global war and kept what the historian John Lewis Gaddis called "the long peace" since 1945, while others have argued that other factors rendered major wars obsolete and that nuclear weapons were a largely irrelevant factor. Many others have argued that the sometimes absurd military postures that the existence of nuclear weapons encouraged greatly and needlessly increased the risk of global destruction and that the peace was maintained despite the existence of nuclear weapons. But whether a positive, negative, or irrelevant force, deterrence has made indelible impressions on the practice of foreign policy and the public imagination.

Bibliography

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— David Coleman

(DOD) The prevention from action by fear of the consequences. Deterrence is a state of mind brought about by the existence of a credible threat of unacceptable counteraction.

A military capability sufficiently strong to discourage any would-be aggressor from starting a war because of the fear of retaliation. (See balance of terror.)

Look up Deterrence in Wiktionary, the free dictionary.

Deterrence can refer to:

• Deterrence theory, a theory of war, especially regarding nuclear weapons
• Deterrence (legal), a theory of justice
• Deterrence (psychological), a psychological theory
• Deterrence (film)

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