Understanding Deterrence

T he challenge of deterrence—discouraging states from taking unwanted actions, especially military aggression—has again become a principal theme in U.S. defense policy. In Europe, the United States and its allies seek to deter potential Russian adventurism in the Baltic states, as well as “gray-zone” activities (ongoing belligerence below the threshold of major war). In Korea, the United States and the Republic of Korea work to deter not only outright invasion but also a spectrum of North Korean provocations. Elsewhere in Asia, the United States and its allies are dealing with Chinese belligerence and gray-zone encroachments on areas subject to territorial disputes. Across the globe and in many different domains, the United States now confronts a more immediate requirement for effective deterrence than at any time since the end of the Cold War. Because many potential adversaries are significantly more capable than they were a decade or more ago, moreover, the risks of actually fighting a major war are more significant than ever—making it even more imperative to deter conflict. Yet much of the emerging dialogue on deterrence remains characterized by unsupported assertions, claims that contradict the empirical record, and little reference to classic analyses.1 Meanwhile, changes in the international security environment have altered the context for deterrence, possibly challenging long-held assumptions and creating new requirements. This Perspective draws on a range of recent and classic RAND Corporation studies to revisit fundamental concepts and principles about deterrence. The most important overarching lesson of this review is that deterrence and dissuasion must be conceived primarily as an effort to shape the thinking of a potential aggressor. Deterrent policies are often viewed through the perspective of the country doing the deterring—in this case, the United States—and focus on actions that it takes to raise the costs and risks of an attack. But the value of those steps depends entirely on their effect on the perceptions of the target state. Any strategy to prevent aggression must begin with an assessment of the interests, motives, and imperatives of the Understanding Deterrence

potential aggressor, including its theory of deterrence (taking into account what it values and why).In the process, as will be argued, history strongly suggests that aggressor motivations are varied and complex, and as often grounded in a desperate sense of a need to act as they are the product of aggressive opportunism. 2Deterrence turns out to be about much more than merely threatening a potential adversary: It demands the nuanced shaping of perceptions so that an adversary sees the alternatives to aggression as more attractive than war.

Definitions and Types
Deterrence is the practice of discouraging or restraining someonein world politics, usually a nation-state-from taking unwanted actions, such as an armed attack.It involves an effort to stop or prevent an action, as opposed to the closely related but distinct concept of "compellence," which is an effort to force an actor to do something.

Denial Versus Punishment
The classic literature distinguishes between two fundamental approaches to deterrence.Deterrence by denial strategies seek to deter an action by making it infeasible or unlikely to succeed, thus denying a potential aggressor confidence in attaining its objectives-deploying sufficient local military forces to defeat an invasion, for example. 3At their extreme, these strategies can confront a potential aggressor with the risk of catastrophic loss.Deterrence by denial represents, in effect, simply the application of an intention and effort to defend some commitment.A capability to deny amounts to a capability to defend; "deterrence and defense are analytically distinct but thoroughly interrelated in practice." 4The most common way of measuring the health of a deterrence threat grounded in denial capabilities is the immediate balance of forces in the contested territory-but, as will be explained, the local balance of forces is not the only, or even always the most important, factor.Deterrence by denial should not be equated with military balances alone.
Deterrence by punishment, on the other hand, threatens severe penalties, such as nuclear escalation or severe economic sanctions, if an attack occurs.These penalties are connected to the local fight and the wider world.The focus of deterrence by punishment is not the direct defense of the contested commitment but rather threats of wider punishment that would raise the cost of an attack.
Most classic studies suggest that denial strategies are inherently more reliable than punishment strategies. 5Steps taken to deny, such as placing significant military capabilities directly in the path of an aggressor, speak loudly and clearly.An aggressor might doubt, on the other hand, a defender's willingness to impose punishments. 6 aggressor might also convince itself that the defender will hesitate to follow through on threats to punish because of attendant risks, such as further escalation, that the deterring state may not An aggressor might also convince itself that the defender will hesitate to follow through on threats to punish because of the attendant risks that the deterring state may not be willing to run once the moment arrives.
be willing to run once the moment arrives. 7As Thomas Schelling noted, there are threats that a state would rather not fulfill, and weakness in deterrence can emerge when an aggressor believes the defender will ultimately prove unwilling to carry out its threats. 8

Direct Versus Extended
Deterrence can be used in two sets of circumstances.Direct deterrence consists of efforts by a state to prevent attacks on its own territory-in the U.S. case, within the territorial boundaries of the United States itself.Extended deterrence involves discouraging attacks on third parties, such as allies or partners.During the Cold War, direct deterrence involved discouraging a Soviet nuclear attack on U.S, territory; extended deterrence involved preventing a Soviet conventional attack on North Atlantic Treaty Organization (NATO) members. 9r obvious reasons, extended deterrence is more challenging than direct deterrence.This is partly true for military operational reasons: It is more difficult to deny an attack far from home, a mission that demands the projection of military force sometimes thousands of miles away and often much closer to the territory of the aggressor state.However, it is also true for reasons of credibility.An aggressor can almost always be certain a state will fight to defend itself, but it may doubt that a defender will fulfill a pledge to defend a third party.During the Cold War, for example, there were constant debates about the credibility of the U.S. promise to "sacrifice New York for Paris." Reinforcing extended deterrence involves taking steps to convince a potential aggressor that the distant defender will definitely respond to an attack, or at least as promptly as it can in accordance with national laws.Such steps include actions like stationing signif-icant numbers of troops from the deterring state on the territory of the threatened nation, as the United States has done in many cases.
The defender seeks to create the perception that it has, in effect, no choice but to respond if its ally is attacked.
Yet this is a demanding standard to meet, in part because a state will seldom commit to anything like an automatic response if vital national interests are not at stake-and often, even if they are.
The most famous cases of extended deterrence failure involving the United States-such as Korea in 1950 and Iraq-Kuwait in 1990can be partly traced to the fact that the United States was unwilling to demonstrate automaticity of response before the fact.Even the most powerful treaty commitments generally contain some degree of leeway.Article 5 of the North Atlantic Treaty, which is arguably the strongest U.S. commitment of extended deterrence, does not oblige parties to take an automatic response to aggression against any other ally.It calls on parties to take "forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area." 10 This language reflected a compromise between the United States' European allies, which sought as close as possible to an automatic response in the event of aggression, and the U.S. Congress, which wanted to preserve its war powers.Similar conditions can be found in all U.S. mutual security treaties.
The United States has sometimes hesitated to make lessambiguous deterrent threats, such as in the cases of Korea and Iraq, because of another complication in extended deterrence (and deterrence threats of all kinds): Such threats can be very costly to make.This is partly true because of the implied commitment involvedonce the United States has threatened to respond to a certain sort of attack, it must then plan and prepare to do so.Much of the current U.S. defense budget is devoted to building the capacity and capabilities necessary to engage in the large-scale contingencies that represent the U.S. global deterrence posture.But threats can also be costly in diplomatic terms, generating deeper tensions with rivals who may or may not have been intending to attack.Defenders, therefore, are constantly engaged in a tenuous balancing act.They are trying to gauge the national interests they have at stake in a potential contingency, the costs and risks of being very explicit about their response, and the dangers of aggression if they do not make such explicit threats.Such complex dynamics are apparent in the U.S. and NATO efforts to warn Russia off aggression in the Baltic states today.

General Versus Immediate
Finally, the theoretical literature distinguishes between two overlapping time periods in which deterrence policies can be employed.
General deterrence is the ongoing, persistent effort to prevent unwanted actions over the long term and in noncrisis situations.
Immediate deterrence represents more short-term, urgent attempts to prevent a specific, imminent attack, most typically during a crisis. 11For example, the United States employed general deterrence for decades by publicizing ongoing promises of defense and punishment if the Soviet Union attacked Western Europe.The United States engaged in the related but distinct task of immediate deterrence during crisis periods, when the United States feared that Soviet aggression against Berlin was imminent.
Most classic studies suggest that general deterrence is easier than immediate deterrence.A potential aggressor may pass long periods without being tempted to take aggressive actions.It is in the specific moments when aggression seems especially enticing or desperately required that deterrence is most at risk, and these moments call for very aggressive and urgent efforts to bolster immediate deterrence.Succeeding during such crises can be especially challenging because the aggressor may have become so committed to a course of action, and so opposed to the idea of backing down, that it has become almost impossible to deter. 12Therefore, part of the goal of general deterrence is to reduce the need for immediate deterrenceto create deterrent and dissuasion effects that become so ingrained that hesitation to attack becomes habitual.

Narrow Versus Broad Concepts of Deterrence
One of the most important decisions about how to view deterrence involves its scope: Is it viewed narrowly or broadly?The narrowest definitions hold that deterrence refers solely to military tools of statecraft-using the threat of military response to prevent a state from taking an action. 13A broader conception keeps the focus on threats but expands the scope to nonmilitary actions: A state can deter using threats of economic sanctions, diplomatic exclusion, or information operations. 14ese two approaches agree with the basic definition that deterrence is "dissuasion by means of threat."It can be based on "the capability of defense denying the adversary its immediate objectives" or on "the threat of inflicting heavy punishment in a larger struggle." 15Either way, it is an effort to affect the calculus of risk and cost by threatening either the potential success or the other interests of the aggressor. 16third, broader way of approaching deterrence is to understand the idea of discouraging unwanted actions as including means beyond threats-to think of deterrence as only one part of a larger process of dissuading an actor.The goal of dissuasion is to convince a potential attacker that the cost-benefit calculus of aggression is unfavorable, partly through emphasizing the costs of aggression but also through offering reassurances and benefits that make a world without aggression more attractive.
It is an approach designed to make aggression as unnecessary as it is costly. 17"In its most general form," Alexander George and Richard Smoke have written, "deterrence is simply the persuasion of one's opponent that the costs and/or risks of a given course of action he might take outweigh its benefits." 18This concept suggests that deterrent strategies can help prevent an action by including steps to make an action unnecessary-including offering concessions or reassurances.
In real-world situations, the United States often combines threats and inducements in this way.In cases of nonproliferation, for example, the United States seeks to dissuade certain states from developing nuclear capabilities by threatening (mostly nonmilitary) consequences-but also by offering possible benefits if that state agrees to constrain its nuclear ambitions.
Using such a broader concept of dissuasion to describe what a deterring state is trying to do turns out to be especially important because of the ways in which threat-based deterrence strategies can go tragically wrong and provoke the very conflicts they are meant to avoid. 19Capabilities deployed to deter, for example, can end up convincing the other side that the deterring state is preparing an attack, making war look more necessary, rather than less.Actions taken to punish an aggressor can create a desperate situation in which the aggressor ends up believing that war is its only option.
In many Cold War cases, for example, such as Berlin and the Cuban Missile Crisis, U.S. leaders ended up undertaking various initiatives to convince the Soviet Union that it would be secure without aggression.Especially when dealing with a peer rival that believes it has a rightful claim to international status, it can be very difficult to merely threaten a potential aggressor into submission.Some form of reassurance is almost always part of any successful dissuasion strategy.
The Local Balance of Forces: Important but Not Always Decisive While potent capabilities for denying aggressors' objectives typically form the foundation of any wider deterrence strategy, the variable of the local balance of forces does not, on its own, consistently explain the success or failure of deterrence.In many cases, potential aggressors never challenged local weakness: The Soviet Union could have seized Norway during the Cold War at just about any time, but chose not to because of the larger ramifications.Sometimes states with dominant power refused to fully deploy it, as with the United States in Vietnam.Viewed strictly in percentage terms, the number of states with a military advantage that do not start wars is overwhelming.In other cases, aggressors ignored clear evidence that the defender was superior and attacked anyway. 20rt of the goal of general deterrence is to reduce the need for immediate deterrence-to create deterrent and dissuasion effects that become so ingrained that hesitation to attack becomes habitual.
Decisions for war reflect a kaleidoscope of fears, goals, preferences, motives, and other considerations.An aggressor's belief about the relative military strength at the point of attack is only one of those factors."Wars rarely start because one side believes that it has a military advantage," the scholar Richard Ned Lebow explains."They occur when leaders become convinced that force is necessary to achieve important goals." 21en if the defender has the advantage, deterrence can fail because aggressors engage in wishful thinking-as Japan did in 1941, convincing itself that it could win a war against the United States.Such wishful thinking often supports an implicit decision that has already been made: The aggressor has determined that, for geostrategic or domestic political reasons, it has to act.In such cases, even a strong military advantage for the defender will not prevent war from occurring.
The defender need not have superiority for deterrence to work.
Sometimes it can be in an inferior position and still succeed even when an adversary is inclined to attack-as NATO was compared with massive Soviet armies during much of the Cold War.The question for deterrence is more complex and nuanced: How much military capability, especially in the local area of potential aggression, is enough to deny an aggressor the opportunity for an easy victory?Both classic deterrence literature and more-recent empiri-cal analyses suggest that the answer need not be an unquestioned ability to "win."A defender can succeed by deploying sufficient local forces to raise the cost of a potential attack, to make escalation inevitable, and to deny the possibility of a low-risk fait accompli.Such a strategy is based on the idea that even incomplete denial capabilities can create the risks of escalation, raising "a specter of costs for the enemy well beyond those which the surface forces themselves are capable of inflicting." 22Even if an attacker believes it might be successful in such cases, the costs of a long and painful war are a powerful preventive deterrent.
The United States employed this strategy with great success in Europe during the Cold War.Glenn Snyder, a member of the original postwar generation of deterrence theorists, recognized as early as 1959 that U.S. forces were "incapable of denying any territory to the Soviets that they wish to take with full force."That was not the forces' main purpose-but nor, on the other hand, were they mere "hostages," a force serving only as a trip wire for U.S. involvement.The sizeable U.S. presence had deterrent value "in its indirect complementary effects-that is, in the extent to which it strengthens the probable or evident willingness of the West to activate the strategic airpower deterrent."These forces could achieve these effects in several ways: by serving a classic trip-wire function, forcing Moscow to kill Americans in an attack; by placing U.S. national In real-world situations, the United States often combines threats and inducements in this way.In cases of nonproliferation, for example, the United States seeks to dissuade certain states from developing nuclear capabilities by threatening (mostly nonmilitary) consequencesbut also by offering possible benefits if that state agrees to constrain its nuclear ambitions.prestige on the line; and by requiring a larger Soviet attack, making a short-notice fait accompli less possible.By playing such roles, Snyder concluded, "[F]orces beyond those necessary for the trip-wire and yet too weak to defend against a full-scale attack nevertheless do contribute to the deterrence of such an attack." 23e Dominant Variable: Perceptions Over the past three decades, further research on deterrence has emphasized a crucial fact: It is the perceptions of the potential aggressor that matter, not the actual prospects for victory or the objectively measured consequences of an attack.Perceptions are the dominant variable in deterrence success or failure. 24e classic, game-theoretic version of deterrence theory was a form of rationalist cost-benefit calculus.It relied for its success on a foundation of the objective, rational evaluation of ends, costs, and risks by a potential aggressor 25 and demanded a shared and coherent value system of clearly defined objectives.Yet more-recent research has made clear that these assumptions often do not hold: Deterrence succeeds, when it does, by creating a subjective perception in the minds of the leaders of the target state. 26e importance of aggressor perceptions explains why deterrence can fail even when a defender has seemingly sufficient military strength.As noted above, potential aggressors sometimes decide that they must act-because they believe they face national ruin otherwise (as in Japan in 1941), 27 because a geopolitical commitment is on the line (as in the Soviet Union in Afghanistan), or because domestic factors make aggression a seeming necessity.
States this powerfully motivated can become essentially immune to deterrence.
History is full of examples of states that seemingly ought to have been deterred nonetheless going to war because they had potent domestic or perceptual reasons for thinking they simply had no choice."Almost without exception," Lebow has suggested, crises "could most readily be traced to grave foreign and domestic threats which leaders believed could only be overcome through an aggressive foreign policy." 28Lebow points to research outlining at least four avenues to perception-driven aggression: the aggressor's fear of a looming collapse in the global balance of power, the need to redirect attention from domestic political instability, the weaknesses of a specific set of leaders, and competition for power among a state's elites.Deterrence strategies will have great difficulty in addressing any of these motives.
Perceptions, in turn, point to the critical role of specific leaders and their preconceptions, beliefs, and cognitive styles. 29Some may be risk avoidant and relatively easy to deter.Others, such as Saddam Hussein, may repeatedly engage in megalomaniacal wishful thinking in ways that make deterrence a constant struggle.
These examples demonstrate the importance of pairing deterrent threats with compromises and reassurances in a larger strategy of dissuasion.Otherwise, the defender's threats can mount to the point that they convince a potential aggressor that it must attack because the deterring power is seeking its destruction.U.S. strategy toward North Korea could run this risk if steps taken to deter end

It is the perceptions of the potential aggressor that matter, not the aggressor's actual prospects for victory or the objectively measured consequences of an attack.
up convincing Pyongyang that the United States is preparing for war.
The importance of perception also illustrates the importance of developing deterrence strategies custom-made for the interests, preferences, and perceptions of a specific adversary.The notion of "tailored deterrence" has gained renewed attention in recent years.
While, in essence, it merely calls for applying classic deterrence notions to specific cases, it is nonetheless a useful reminder that deterrence does not work in general-it works in specific ways against specific potential aggressors.As the unclassified public version of the 2018 U.S. nuclear posture review put it, There is no "one size fits all" for deterrence.The requirements for effective deterrence vary given the need to address the unique perceptions, goals, interests, strengths, strategies, and vulnerabilities of different potential adversaries.The deterrence strategy effective against one potential adversary may not deter another. 30

Deterrence
Hundreds of studies on deterrence-some entirely theoretical, some grounded in game theory, some based on large statistical analyses of deterrence cases, and some grounded in detailed case studies of specific examples-identify three essential factors as the most important determinants of the success or failure of deterrence strategies.

Level of Aggressor Motivation
As suggested by the importance of perceptual variables to deterrence, the intentions of the potential aggressor are the beginning point for any analysis of deterrence success or failure.If a state sees little reason to undertake aggression, it will not be hard to deter; if it has acquired an urgent sense that only an attack will safeguard its interests, it may become almost impossible to stop.Patrick Morgan concludes that "challenger motivation is the most important factor in deterrence success or failure." 31ssible motivation to attack can stem from many perceptions, not all of them opportunistic.In fact, the degree to which a potential aggressor is dissatisfied with the status quo is one of the most powerful engines of aggressive intent.A state that believes that it is being constricted to the point of regime collapse, such as Iraq in 1990 or Japan in 1941, will accept many more risks than a state that believes it can achieve its national goals without war.
The empirical record strongly indicates that states that initiate aggression are not merely opportunistic or aggressive but are often responding to situations they perceive as highly dangerous.Combinations of threats and concessions appear to be most associated The notion of "tailored deterrence" has gained renewed attention in recent years.While in essence it merely calls for applying classic deterrence notions to specific cases, it is nonetheless a useful reminder that deterrence does not work in general-it works in specific ways against specific potential aggressors.with deterrence success; as one scholar has concluded, "Mixing deterrence and conciliation is best-be tough but not bullying, rigid, or unsympathetic." 32ese decisions are typically comparative rather than binary.
Decisionmakers seldom weigh the cost-benefit calculus of starting aggression in the abstract; they are considering the relative merits of several alternative courses.If leaders view attacking as less risky or costly than any of the alternatives, they will not be deterred.But this comparative decisionmaking process also suggests, as Schelling argued, that "the pain and suffering" embodied in the deterrent threats "have to appear contingent on their behavior." 33If deterrent threats come to be perceived as a general policy of hostility, they may lose their ability to be applied to deter specific actions.

Clarity About the Object of Deterrence and Actions the Defender Will Take
A second broad criterion for deterrence success is that the defender should be as clear as possible about what it is trying to deter, as well as what it will do if the threat is ignored. 34Korea in 1950 and Iraq in 1990 provide two powerful examples of the dangers of a striking absence of clarity.In both cases, the United States refused to be clear in its deterrent threat.This failure left two highly motivated aggressors ample room to convince themselves that they could achieve a fait accompli that would not provoke a decisive U.S.
response.By its nature, deterrence is a demand that another state refrain from doing something.The more ambiguous the demand is, the more chance there is for failure in the deterrent policy.
Not only must the deterring state be precise in its commitments, but its target must understand them clearly.A key challenge of deterrent threats is to ensure that a potential aggressor perceives the message "through the din and noise" of world politics. 35This demands both public and private efforts to communicate an unambiguous message.It also points to the danger of statements or actions that seemingly throw into doubt the sincerity of the commitment.
Yet as explained earlier, making unqualified deterrent threats can be costly, both in terms of the military requirements they generate and because of the hostility and tensions they provoketensions that can end up making a conflict more rather than less likely.States trying to deter attack must always balance these essential considerations, trying to find the degree of clarity that will make their intentions apparent without provoking.And in the process, the defender is always calculating the degree of national interests involved: It may prefer not to see a certain form of aggression, but if the target of that attack is not vitally important to the deterring state, it will seldom be capable of broadcasting unambiguous deterrent threats in peacetime.

Capability and Will to Carry Out Threats
Much of classic deterrence theory can be boiled down to a simple proposition: The potential aggressor must believe that the defender has the capability and will to do what it threatens. 36This criterion is, again, perceptual: The question is not whether the defender If deterrent threats come to be perceived as a general policy of hostility, they may lose their ability to be applied to deter specific actions.
actually has such capabilities or will, it is whether the aggressor believes that it does.Deterrence depends on the perception of the "threatener's determination to fulfill the threat if need be"-and, more importantly, on the potential aggressor's "conviction that the threat will be carried out." 37Deterrence fails, Bruce Russett concludes, "when the attacker decides that the defender's threat is not likely to be fulfilled." 38This axiom highlights two distinct factorscapability and will.Perceived weakness in either can undermine deterrence.
Capability is straightforward enough.As suggested earlier, the immediate, local balance of forces is not always a key determinant of deterrence success-but a defender's broadly perceived suite of capabilities, military and otherwise, must be strong enough to convince a potential attacker that it is likely to pay a heavy price for aggression.Will is a much more abstract variable and easily subject to misperception.Aggressors have repeatedly convinced themselves that a defender did not have the will to respond, especially in cases of extended deterrence.Will is partly a function of the national interests involved: If a defender is seen to have vital interests at stake, a potential attacker will believe threats of response.
Aggressors can try to undermine a defender's willingness to respond by using "salami slicing" approaches-using a long series of low-level aggressions to change the facts on the ground without ever taking action that would justify a major response.Such strategies are designed to put the defender in a dilemma: It cannot respond to every small violation, but if it does not begin to punish minor transgressions, its strategic position will erode over time.The United States confronts this challenge with Chinese and Russian gray-zone campaigns today.
As noted earlier, classic deterrence theory spoke in terms not only of making credible threats but also, where possible, of creating a perceived obligation to respond.Schelling believed that, once a war loomed, the deterring state would often want to avoid the consequences of its commitments by wriggling free of its deterrent threats.
Anticipating this, some aggressors can convince themselves that threats will be abandoned once the risks grow too high, and deterrence can thus fail even when rhetorical commitments are in place.
Sustaining a potential aggressor's belief in the threats became a major preoccupation of the deterrence literature, and Schelling brought the line of thinking to its natural conclusion: In order to deter, stating a commitment is not enough; a defender must show that it has no choice but to react. 39The literature suggests several specific mechanisms for creating such unbreakable commitments: making clear public commitments and staking national prestige on a powerful response; agreeing to formal treaties of mutual defense; deploying trip wire forces; constructing a basing and logistical infrastructure that signals an intent to reinforce in case of war; and selling arms to the threatened state to reinforce defense ties. 40Yet as noted above, creating commitments that cannot be abandoned imposes very significant political costs and will often be more than a defender is willing to do in peacetime.
Finally, one long-held claim about the credibility of deterrent threats has now been largely discredited: the idea that a state's general reputation for toughness and resolve is essential to deterrence.This claim supported the idea, which guided much of U.S. Cold War policy, that no example of Soviet aggression could be ignored.
Because reputation was thought to accumulate through individual actions, standing firm across the board seemed essential.

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About This Perspective
The challenge of deterrence-discouraging states from taking unwanted actions, especially military aggression-has again become a principal theme in U.S. defense policy.Yet much of the emerging dialogue on deterrence remains characterized by unsupported assertions, claims that contradict the empirical record, and little reference to classic analyses.This Perspective draws on a range of recent and classic RAND Corporation studies to revisit fundamental concepts and principles about deterrence.The most important overarching lesson of this review is that deterrence and dissuasion must be conceived primarily as an effort to shape the thinking of a potential aggressor.Any strategy to prevent aggression must begin with an assessment of the interests, motives, and imperatives of the potential aggressor, including its theory of deterrence (taking into account what it values and why).Deterrence turns out to be about much more than merely threatening a potential adversary: It demands the nuanced shaping of perceptions so that an adversary sees the alternatives to aggression as more attractive than war.
This perspective represents the views of the author and is partly informed by a wide range of RAND Corporation work on deterrence.The author would like to thank his RAND colleagues Karl Mueller and Steve Flanagan, who reviewed this publication and provided extremely helpful recommendations for its improvement.

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About the Author
Mike Mazarr is a senior political scientist specializing in U.S. national security strategy, the Korean Peninsula, and issues such as risk and strategic planning.He came to RAND in November 2014 from the U.S. National War College, where he was a professor and associate dean.He has worked at research institutes, including a decade at CSIS and a period as president of the Henry Stimson Center; as a senior staffer on Capitol Hill; and as special assistant to the Chairman of the Joint Chiefs.He is a former Naval Reserve intelligence officer.
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