Deterrence by Denial: Theory and Practice edited by Alex S. Wilner and Andreas Wegner. Cambridge University Press, 2021, 282 pp.
The rise of nuclear-armed superpower adversaries during the Cold War prompted theorists to produce a rich body of literature on the concept of deterrence. But they favored the study of deterrence through punishment by nuclear weapons to the point that other forms of deterrence, notably deterrence by denial, went undertheorized.
Amid a geostrategic environment in which deterrence has taken on new salience, Alex S. Wilner and Andreas Wegner produced a volume of essays that is a timely addition to the theory of deterrence by denial. To advance the study of the concept beyond its infancy, they assembled an international group of scholars of political science, international relations, and strategy.
At the start of the volume, the editors and distinguished theorist Patrick Morgan explain what ostensibly is a straight-forward concept. Whereas deterrence by punishment attempts to influence a challenger’s decision calculus by imposing costs for that action beyond what the challenger is willing to pay, deterrence by denial affects the other side of the balance; it denies the proposed action’s benefits. The concept is seemingly useful in our era of great power competition where security threats thrive but do not rise to the threshold of nuclear exchange.
Nevertheless, without the overwhelming clarity of mutual assured destruction, theorists have been ambiguous about its application and effects. The case studies illustrate the challenge of identifying a cause-and-effect relationship between a defender’s denial efforts and a challenger’s decision refrain from action, casting doubt on the utility of the concept as it is formulated by the volume’s contributors.
Dima Adamsky’s article on Israeli concepts of deterrence exhibits the difficulty of parsing out the concept’s working from the tangle of actions and counteractions taken by opponents in real-world conflict. The thrust of Adamsky’s chapter is that, in their conflict with the Arabs, the Israelis shifted from punitive deterrence to static defense once it became clear to Israeli strategists that punitive operations were losing their deterrent effect.
He claims that deterrence by denial became more prominent after the Israelis made the shift. Yet, his descriptions of Israeli missile defense and civil defense advances are not connected by argument to enemy decisions to abandon intended attacks. He does not analyze the enemy’s decision calculus or its interpretation of Israeli actions. Lost in his discussion is a cause-and-effect analysis that shows the intentionality of Israeli deterrence by denial, how the deterrent message was understood by enemies, and how that understanding shaped their actions. Jonathan Trexel’s article on Japanese ballistic missile defense vis-à-vis North Korea suffers from a similar lack of evidence-based argumentation.
While Adamsky and Trexel are unconvincing in showing the action of the concept in their case studies, James J. Wirtz hampers the editors’ goal of gaining “a better understanding of the conceptual distinction and relationship between defense, deterrence by denial, and deterrence by punishment” (212). In a chapter on the strategy of deterrence by denial, Wirtz blurs the theoretical distinction between defense and deterrence. He posits an idiosyncratic typology that makes deterrence a subset of defense. Writing of “defense by deterrence,” he makes deterrence instrumental to something from which the editors hope to distinguish it (124, 140).
He may have in mind a grander conception of defense, such as that implied by the title of the Department of Defense, but he refrains from defining it. Regarding deterrence by denial, he recommends to US policy makers a sort of second-order strategy of denying challengers’ attempts to circumvent American deterrence efforts. In essence, Wirtz recommends defending US deterrence activities from attacks by adversaries. The suggestion, again, conflates defense and deterrence. Overall, Wirtz’s chapter gets lost in its layers of abstraction, obscuring rather than clarifying the concept.
The best chapters in the volume evaluate deterrence by denial critically. John Sawyer, who analyzes its applicability to counterterrorism, and Martin Libicki, who evaluates its relevance in cyberwar, each provide insights into the broad concept that extend beyond the circumscribed subjects of their chapters.
Sawyer analyzes the logic by which deterrence by denial functions and finds it should be reclassified as “dissuasion by denial.” Sawyer begins by defining three approaches to preventing or mitigating terrorist attacks: offense, defense, and influence. Deterrence falls under the influence approach, which is, in turn, subdivided into “bundling” and “dissuasion” logics. On the one hand, bundling consists of if-then relationships between adversaries; for example, “if you do x, I will respond with y”; “if you do stop doing x, I will not do y,” and so on.
On the other hand, dissuasion seeks to alter the attacker’s perception of status quo as it pertains to the costs and benefits of a prospective attack. Sawyer argues that deterrence by punishment is an example of bundling; but, in contrast, deterrence by denial fits under the logic of dissuasion. It is better classified as dissuasion by denial: “manipulating perceptions of the ability to access and attack a given target using a given tactic” (109).
By removing deterrence by denial from the if-then logic within which it does not fit, Sawyer makes it a more useful concept. Dissuasion by denial becomes more than the other side of the cost-benefit equation. Instead, it operates on the present environment, not in the future, and it operates independently of the defender’s threats. By grouping dissuasion by denial with other forms of dissuasion, Sawyer opens the way for the fruitful application of denial to a larger dissuasion effort. Furthermore, he clarifies the logic of the concept, which up to this point, he correctly notes, has been “an untenable and confusing mishmash of the bundling, dissuasion, and offense logics” (108–09).
In his chapter, Martin Libicki makes points about information and understanding that transcend his subject of deterrence by denial in cyberspace. He argues that militating against it is the difficulty of opponents to know each other’s capabilities when contemplating attack or defense. Opponents struggle to discern the deterrent effect of a defense and attackers can only know if a target is impenetrable by attempting to penetrate it (196). They often do not know the scope of a defender’s defenses or if an attack succeeded and, if so, what the consequences are.
A study of military history would demonstrate such uncertainty on the part of an attacker to be the case of any conflict. Moreover, Libicki shows that in cyberwar, a challenger front-loads costs so that its chances for success against a defense will be good when it is time to strike. Therefore, it is the challenger’s perception of his own preparations, not the quality of the defender’s defenses, that determine if the challenger will strike. The result, Libicki concludes, is that the prospects for deterrence by denial are dim in cyberspace. Overall, Libicki’s work indicates fruitful paths for research on deterrence in other domains.
The editors of Deterrence by Denial intend it for “policy makers, practitioners, analysts, and academics,” but it is likely of marginal value for officials seeking to translate theory into plans (281). The volume elaborates and expands the concept of deterrence by denial without giving it greater power to guide decision-making. The contributors lack a common lexicon and typology to discuss it.
Their various analyses are often unclear about who is being deterred, what action is being deterred, or when deterrence starts or ends. They do not offer evidence that would assure those seeking to practically apply the concept. To make progress, analysts should generate longer and richer narratives that illustrate the concept’s impact on events and why it was deterrence by denial and not some other contingency that shaped the course of a given conflict.
All the same, Deterrence by Denial is a contribution to the growing literature on this concept. In elaborating the theory and in its short case studies, it serves as a guidepost for the work that needs to be done in developing this concept, which is of salience amidst today’s great power competition.
Richard Marsh, PhD