Eric Gartzke and Jon Lindsay have written a profoundly important book, one which is complex and dynamic in its theoretical arguments about the combinatorial logic of deterrence. It is a must-read for anyone interested in strategy and grand strategy. Their sophisticated analysis reminds us that politics matter because deterrence cannot be all things to all people. Different means are often best suited to different ends and at times one means can compromise another. It is political leaders who choose the goals that matter most. Military leaders must then configure the means to best achieve these goals and, at a minimum, not compromise their achievement. The authors conclude that the “problem of political preferences trumps the issue of technological complexity. There is no meaningful “right” way to combine the means of competition and conflict without a clear sense of preferred political ends” (pp. 374–375). Politics matters because it is through politics that we choose among difficult trade-offs. And success in deterrence, they tell us, comes only by facing these difficult trade-offs and making hard choices. In this, their most fundamental argument, Gartzke and Lindsay have it exactly right.

How do the authors get there? The foundation of their argument is that differentiated instruments—the “means” of deterrence—tend to be specialized for different objectives—political influence, military effectiveness, managing cost (which they describe as policy efficiency), or strategic stability. Different strategies—accommodation, coercion, defense, and deception—are most effective in achieving each of these four goals respectively. The book puts to one side accommodation and explores how the means that are necessary to coerce, defend, and deceive do not fit easily together and create trade-offs. It is these trade-offs among means that create the imperative to choose among goals and strategies. If all the means were fully compatible, we could have it all. But, the authors argue, they’re not, so strategists cannot do it all.

The originality of the argument lies in how the authors show that the means of deterrence—drones, naval forces, forward deployments—send different signals that work differently to accomplish coercion, defense, or deception. Using them all at once and all together can work to undermine any one of the strategies. Grand strategy, Gartzke and Lindsay tell us, is interested not only in winning but also in warning, watching, and working. A significant forward deployment of land forces enhances warning by providing a costly signal of commitment, but it is costly. Mobile naval forces are effective at projecting power (winning), but far less effective as signals of resolve (warning). Heavy reliance on inexpensive drones reduces risk to military personnel (winning) but sends a weak signal of resolve. The book is rich in these kinds of arguments supported by both experimental and historical evidence. A brief review cannot possibly do justice to the complexity of the combinatorial logic and the trade-offs and contradictions they create.

I read this volume not only as an examination of the strategy of deterrence and its elements, but also, and perhaps more significantly, as a volume about grand strategy in which deterrence figures as an important component. Gartzke and Lindsay as much as tell us that when they argue that leaders are interested not only in deterrence but in grand strategy (p. 383). Those who seek to deter an adversary from changing the status quo will bolster the credibility of threats through forward deployments that are costly signals. Leaders like President Biden whose priority in Ukraine was to control escalation with Russia will tend to minimize risks and avoid using forward deployments precisely because they are costly signals that can be so easily misread. Those whose priority is to gain or maintain a favorable balance of power should maximize war-fighting effectiveness by deploying highly lethal and mobile multidomain forces, particularly in the air and at sea. And those who need to economize should focus on information and deception in space and cyberspace.

This advice generates three research agendas, one at the level of strategy, the second at the level of grand strategy, and the third related to the psychology of trade-offs. When designing a strategy of deterrence, a leader needs to use military means that are costly signals of resolve but do not provoke an adversary to escalate. That balance is exquisitely hard to calibrate, and leaders must be constantly aware of the trade-offs among means. The challenge then is not to choose between two priorities, deterrence and avoiding escalation—deterrence fails if an adversary escalates. It is rather to choose the combination of means that is most likely to enable deterrence to succeed without provoking escalation in a particular context. Gartzke and Lindsay, in their future research, need to work through the combinatorial logics that avoid the worst of the trade-offs that are so severe that they can compromise the achievement of a strategic priority. And to make matters even harder, as the authors tell us, deterrence can fail over time. It can fail later in a different way because it succeeded earlier. Identifying the right combination of means becomes a sequential as well as a simultaneous task.

The second research agenda is at the level of grand strategy. Here too, the authors need to tell us more about the trade-offs when leaders sequence strategies within a larger grand strategy. Are some of the trade-offs among means then attenuated? Leaders who seek to deter also want to be able to fight and win after deterrence fails. The argument then changes from one about the simultaneous use of multiple means to deter to the use of one set of means to deter and then a different set to fight and win a war in the wake of deterrence failure. Sequencing likely reduces some of the trade-offs but does not completely eliminate them. In their future research, Gartzke and Lindsay need to separate more sharply the means deterrence needs for effective coercion that do not provoke escalation and work through the trade-offs among different combinations of these means. They then need to nest the strategy of deterrence within the larger context of grand strategy and identify the danger that the build-up of some of the means required by a grand strategy to prepare for the contingency that deterrence might fail in the future could confuse an adversary and inadvertently contribute to deterrence failure in the present.

Finally, there is the core question of encouraging leaders to face rather than hide from trade-offs. As the authors acknowledge, leaders have bureaucratic and political reasons to postpone choice. They also have powerful psychological reasons to hide from trade-offs, which explains why doing so is the default. Gartzke and Lindsay correctly write that “No technology or combination of technologies can realize all desirable objectives at the same time, to the same degree. Therefore, deterrence cannot be ‘integrated’ for all ends, ways, and means… But waiting for a crisis to figure out what matters is a recipe for miscalculation and deterrence failure. Deferring is not deterring” (p. 376). But ignoring and deferring is exactly what leaders do and no one has yet solved that problem, perhaps because most people, most of the time, hate making trade-offs. This superb book leaves its readers with that wicked problem unsolved.