The United States is a highly polarized country. Its contemporary politics are characterized by “us versus them” thinking and hostility toward members of the opposite party. Meanwhile, civil–military relations in the United States have, in recent times, been the subject of much debate and, particularly among civil–military relations scholars, worry. From Gen. Mark A. Milley’s walk across Lafayette Square with Trump to the dangerous precedent set by both Trump and Biden in appointing recently retired military officers to lead the Department of Defense, the twin trends of affective polarization among the American public and the politicization of US civil–military relations are a recipe for disaster. Yet such events and broad political polarization coincide with continued confidence and trust in the US military, particularly relative to other institutions like Congress, the presidency, the courts, and the media.

This is the setting that Michael A. Robinson enters with his new book, Dangerous Instrument. As part of the “Bridging the Gap” series of Oxford University Press, Robinson asks several questions: “With whom does the military have credibility, and why? What are the limits of that credibility, and how does this reflect the depths of polarization? What are the implications of such deference to the armed forces on the future of democratic governance?” (p. 3). Robinson’s answers to these questions are, from the perspective of healthy democratic civil–military relations, troubling.

Robinson introduces a new model, the “parallax model,” to help us understand and provide terminology for the politicization of the military in US politics. It focuses on three main actors: the military, the public, and the partisan political establishment (p. 37). Simply put, the public’s views of the military—seeing the military on an ideological spectrum—are based on the perceived position of the military relative to political parties. Robinson introduces four types of politicization—active, passive, relative, and aspect politicization—to capture the degree to which the military is actively involved in politics or is thrown into politics by politicians, whether the politicization is a result of shifting ideological currents in the American public, or whether dimensions of the partisan information environment (especially the media) render the military closer to one end of the ideological spectrum (pp. 39–46). The politicization does not need to be intentional, either on the part of the military or politicians, or indeed “real,” in the sense that much of it depends on perceptions. Further, all four types of politicization from the parallax model can occur at the same time. This renders fixing the problem quite difficult but also allows scholars and policy makers to have a more precise vocabulary for discussing politicization, while also enabling researchers to better trace the “cascading effects” (p. 172) of different types of politicizing activity to other forms of politicizing activity.

Dangerous Instrument’s empirical chapters examine and test several aspects of Robinson’s theory. First, chapter 3 demonstrates that military voices are “co-optable.” Using a survey experiment, Robinson shows that the military is a voice that is worth co-opting for partisans because the public deems military voices to be highly credible. Chapter 4 uses text analyses (topic modeling) to shows that negative military performances received less attention in conservative media than in liberal media. Partisans receive different information about the military, and this has downstream consequences for how the military is viewed by those on the Left or Right and for questions of accountability. Chapter 5, again using survey experiments, shows that Democrats and independents “update” their information about the military when told about scandals and negative information about it, whereas Republicans do not. Finally, chapter 6 shows that partisans only seem to care about partisan activity on the part of retired military officers when the military officer is of the “wrong” type (e.g., a Democrat assessing a Republican or vice versa). Taken together, these chapters demonstrate that the military is (1) capturable by partisan politics, (2) portrayed and received differently across the political spectrum, and (3) therefore not immune to politicization.

This book is an excellent contribution to the literature on US civil–military relations. It expertly weaves together insights from American politics and civil–military relations and uses advanced experimental and text analysis techniques and analyses of survey and media evidence. Given the book’s ambition and use of multiple survey experiments, however, it was sometimes difficult to keep all the moving parts coherently together. Furthermore, as Robinson acknowledges, the use of survey experiments lends strong causal identification but just provides snapshots in time. On this score, I thought the book could have given the reader a broader, more historically contextualized, picture of what we are seeing today in the United States.

Something I particularly liked about the book was the effort not just to characterize the problems of polarization and politicization but also to speak to potential solutions and best practices (chap. 7). Robinson offers many solutions, including but not limited to (1) making future officers more politically literate; (2) providing opportunities for officers to engage with civilian officials and enhance a more general public understanding; (3) adopting new perspectives on civil–military relations, including looking abroad for more cross-national understandings of civil–military relations; (4) ensuring that the public understands the difference between active-duty and veteran service members and military-looking individuals (e.g., militia members) and actual members of the US armed forces; and (5) making the military a “harder target” for politicization, including preventing extremism and educating the rank and file in digital literacy (p. 174–91). These suggestions are surely correct and are, importantly, actionable. The recommendations ask something of those within the military and of civilians.

It remains to be seen, considering the trends Robinson identifies in the book, how long the US public will continue to show strong support and confidence in the military. Republican politicians, from Tommy Tuberville to Matt Gaetz, have used the military and its supposed “woke” policies as part of an ongoing culture war. This has led to recent declines in trust in the military among Republicans, a trend that will likely continue. Given the clarity and thoughtfulness of Robinson’s text, people on both sides of the civil–military relationship, as well as scholars interested in the health of American democracy, should read this book.