For over a decade, through a series of influential articles, Christopher Layne has been the leading advocate within the academy of an entirely new and much more detached foreign policy strategy for the United States, one based upon what he calls “offshore balancing.” In The Peace of Illusions, Layne puts his argument in book form, addressing conceptual as well as historical and policy issues.

Layne begins with the question of theory, and asks how we can explain past and current developments in American grand strategy. In particular, he surveys various possible explanations drawn from neorealism. Realists believe that a state's strategic choices stem primarily from changes, opportunities, and constraints within the international system, materially defined. Indeed, some realists give the impression that such choices flow overwhelmingly from international conditions. Layne, on the other hand, wants to argue that while international conditions such as the distribution of power might predict certain optimal strategies, states are still free to choose differently and even badly, for example, for domestic or ideological reasons. In the case of the United States, because of its relative invulnerability to conventional military threats, Layne suggests that the optimal and expected realist strategy would, in fact, be a generally noninterventionist approach in relation to European and Asian security matters, but that at least since the 1940s, the United States has instead followed an extremely ambitious and dysfunctional strategy of global or “extra-regional hegemony” (pp. 3, 23–24). He calls this a form of “Open Door” expansionism, drawing on a long tradition of revisionist work in U.S. diplomatic history (pp. 29–32). According to the author, Open Door ambitions dictate that the U.S. promote an international system characterized by ideologically and economically friendly governments. In the terminology of international relations theory, such ambitions are a unit-level factor. The explanation for America's extraordinarily advanced global role over the past 60 years therefore lies in the specific intersection of international and domestic factors: American power acts as a permissive cause, while Open Door ambitions act as motivation.

This theoretical argument provides the framework for Layne's historical and policy analysis, which form the majority of the book. On the historical side, he argues that the United States possessed a driving determination to achieve global hegemony, and to reduce all potential rivals, even before the conclusion of World War II. This determination, according to Layne, was itself a major cause of Cold War competition with the USSR; it has also consistently dictated that Western Europe be prevented from developing into a serious strategic rival. He completes the historical analysis by arguing that the United States has—somewhat surprisingly—continued to act as a hegemonic power overseas since the end of the Cold War, in spite of the disappearance of the Soviet threat. He suggests that this ongoing hegemonic role has mainly caused resentment abroad, and that other great powers are bound to reemerge and challenge U.S. hegemony more seriously regardless of America's benign self-image. He concludes with policy recommendations for a drastically reduced U.S. military presence overseas, including the dismantling of most of America's Cold War bases and alliances in Europe, Northeast Asia, and the Middle East.

Layne does an especially good job of addressing the gaps and expanding the predictive utility of recent realist work on hegemony, grand strategy, and the balance of power. Here, he is part of a welcome trend toward realist studies that incorporate domestic or unit-level factors into their explanations in a manner that is precise, rigorous, and contextualized. He makes clear predictions, differentiates the conditions under which various strategic choices should be made, and develops criteria for testing whether states in fact follow the predicted strategies. And on the issue of whether the United States has for all practical purposes attempted to pursue a strategy of extraregional hegemony, Layne's analysis is quite convincing: The United States has been an extraregional hegemon since the 1940s; its liberal internationalist or Open Door tradition has encouraged it to try and reshape the international system; this same tradition has often led it into strategic overexpansion; the United States should therefore be more selective about where and when it intervenes militarily. All of this is true. The question is then how far to take these arguments, before they become overstated. For example, while Franklin Roosevelt did hold extremely ambitious postwar goals while fighting World War II—namely, to remake the international system in a more liberal direction—he was not prepared to contemplate a permanent U.S. military presence in Europe after the war's conclusion. Indeed, he hoped that Britain and the USSR, between the two of them, would manage a liberal European order in the postwar era. So while FDR sought in the abstract to liberalize the European state system, he was unwilling to admit that the United States would have to remain a European power after the war in order to secure those liberal goals. This is a common pattern in U.S. foreign policy: extremely ambitious goals, initially unmatched by proportionate means. The rise of American hegemony has therefore been frequently more confused, half-hearted, and improvised than Layne lets on.

The conceptual root of the author's historical and policy analysis seems to lie in the assumption, made early on, that a strategy of military disentanglement and nonintervention is now and almost always has been the optimal “realist” strategy for the United States. Layne is to be commended for making this explicit, but the assumption is unconvincing. Classical realists, such as Walter Lippmann and Reinhold Niebuhr, warned against aggressive, crusading idealism in foreign affairs, but they also warned just as strongly against the belief that either American interests or American values can be protected through a foreign policy posture of strict nonentanglement. That is why they supported U.S. engagement in Europe in the 1940s. Most realists today try to strike the same balance—criticizing, for example, misadventures such as the current war in Iraq, while remaining committed to America's basic posture of “forward defense” in Europe and Northeast Asia. Layne is right to criticize many of America's military interventions in recent years. But the U.S. presence abroad remains fundamentally a linchpin of international peace and stability, as even many of its critics know, and if the United States were actually to follow his advice and disengage from its overseas alliance system altogether, the cure would probably be worse than the disease.

While Layne is unlikely to convince internationalists of either the liberal or the realist variety, his work remains notable for its exceptional clarity, scope, and integrity. The very process of answering his arguments will force internationalists to sharpen their case and admit their own excesses. The Peace of Illusions combines deep historical reading with rigorous theory building and bold policy prescriptions. It is undoubtedly the most serious scholarly argument in many years for a U.S. policy of strategic disengagement, and should be considered required reading for students of international relations.