The Massachusetts Institute of Technology has long been considered one of the finest institutions of scientific learning in the world. But few outside of academia know that MIT’s political science department, and especially its international relations (IR) program, is one of the best around. Neither are many aware that its IR faculty has been ironically old-fashioned—some would wrongly say “unscientific”—in stressing history along with the more technical aspects of defense policy.

Some of the most exciting work in IR has been pursued at MIT over the last few decades. The school has excelled in the study of grand strategy, defined by MIT professor and Restraint author Barry Posen as a state’s “theory about how to produce security for itself.” When the Soviet Union fell, Harvey Sapolsky, longtime director of the university’s security studies program, began to think about what type of grand strategy would be appropriate for the U.S. in the new post-Cold War world. He was joined by two of his graduate students, Eugene Gholz (now a professor at the University of Texas) and Daryl Press (currently a professor at Dartmouth College).

They were not buying the consensus view that the “unipolar moment” meant that the U.S. should double down on its Cold War activist foreign policy. Instead, in their seminal article “Come Home, America,” these three argued that the country needed a grand strategy of “restraint” that harkened back to America’s traditional and Washingtonian approach of noninterventionism.

What the “MIT School” of grand strategy—if you will—lacked was a book-length treatment to do battle with rival approaches. Not until Posen joined the cause with Restraint did the restrainers get a defining treatise.

Posen depicts the current grand strategy debate as pitted between two main rivals: liberal hegemony and restraint. Liberal hegemony is an activist grand strategy that aims to assertively maintain U.S. dominance and the “unipolar moment” in the service of liberalism and national security. Posen explains that it has been the reigning U.S. grand strategy since the end of the Cold War and remains the consensus view of the foreign-policy establishment of both major parties—of liberal internationalists and neoconservatives alike. Yet he believes it is “unnecessary, counterproductive, costly, and wasteful,” and ultimately “self-defeating.” Posen therefore spends the first half of the book explaining in detail what liberal hegemony is and why it so imperils America. In the book’s second, meatier half, he lays out his overarching restraint strategy and describes the specific military approach required to support it.

Restraint begins with a chapter that lays out key facts about the strategic position of the United States: the U.S. is “enormously powerful”—though “change is coming,” geography favors the U.S. due to its “ocean barriers and relatively weak neighbors,” and our nuclear arsenal means that nuclear and conventional attacks on the U.S. are either “suicidal” or “incredibly risky.”

Posen then proceeds to explain the twin pillars of liberal hegemony. First, it is hegemonic since “it builds on the great power advantage of the United States relative to all other major powers and intends to preserve as much of that advantage as possible.” It achieves this by building overwhelming military strength that dissuades potential challengers from even trying to compete with the U.S. and managing American-dominated security relationships across the globe.

Second, liberal hegemony is liberal, Posen explains, because “it aims to defend and promote a range of values associated with Western society in general and U.S. society in particular.” Democracy looms large among these values, particularly because this approach identifies “failed states, rogue states, and illiberal peer competitors” as the primary source of threats to the U.S. and global peace. In short, these latter-day Wilsonians believe that “the United States can only be truly safe in a world full of states like us, and so long as the United States has the power to pursue this outcome, it should.”

Posen argues that this strategy has not performed very well in the post-Cold War era and will only “perform less and less well” in the changing world of the future. Liberal hegemony has been, and will continue to be, quite costly in terms of blood and treasure: the U.S. has fought four wars since 1992, spent trillions of dollars in these conflicts and on maintaining the armed forces, and has suffered great opportunity costs in the process.  Liberal hegemony provokes other states to engage in “sustained obstructionism,” if not outright balancing against the U.S., and it has incentivized our allies, such as NATO and Japan, to “cheap ride” when they could contribute more—thus making the benefits of U.S. security commitments incommensurate with the costs.  Worse, some allies, such as Israel and Iraq, are “reckless drivers” that “do the wrong things,” and the U.S. has little ability to rein them in.

A key original point by Posen is that liberal hegemony does not properly take into account the difficulties posed by identity politics since the French Revolution, and therefore U.S. efforts to shape the world are upended by nationally, ethnically, and religiously motivated forces. Posen also notes that the humanitarian interventions supported by liberal hegemonists—which he admits might be worth undertaking in rare cases for philanthropic rather than strategic reasons—are complex and difficult to execute with military power, especially when they go beyond remedying basic humanitarian crises.

Posen finds the benefits of an activist foreign policy are overstated. The U.S. is incredibly secure, and few foreign issues really have an impact on our interests in any significant fashion—even if they do have an impact on others’.  As Posen explains, liberal hegemonists rely on a problematic domino theory to overstate the interconnectedness of events and how they relate to U.S. security concerns. Their case for the importance of maintaining a hegemonic position for U.S. economic interests is also overblown.

Restraint, Posen’s alternative to liberal hegemony, is developed in the second chapter. He begins with a discussion of U.S. security interests—which include “sovereignty, safety, territorial integrity, and power position”—and then carefully considers potential threats and how to meet them. Primary among these would be “the rise of a continental hegemon” that upsets the “Eurasian” balance of power; nuclear weapons, especially in the hands of terrorists; and “terrorist organizations that have global ambitions.”

Posen thinks there is little risk of the first threat actually materializing since “Today there is no candidate for hegemony in Eurasia.” This is one reason why the U.S. can, in phases, pare back its commitments and reduce its global military footprint. As for the threat posed by nuclear weapons, he thinks the U.S. needs to deter both nuclear attacks by other states and the transfer of nuclear materials to terrorists, and the U.S. should help other nuclear states secure their weapons. Posen finds little support for the view that “crazy states” cannot be deterred, an assumption used to legitimize arguments for preventive war. (Posen is not so sanguine about the robustness of extended deterrence, however: hence he believes the U.S. should be wary of commitments that might be put to the test.) Lastly, Posen appreciates the need to take active steps against international terrorists, including intelligence collection, the use of force—especially special operations and drone strikes—and diplomacy. But he points out that U.S. forward-deployed troops and large operations can in many cases make things worse.

Posen proceeds to define what restraint would look like in the various regions. In Europe, he believes it is “past time to realize the dividends” of our Cold War victory. This means the U.S. can withdraw its forces, transfer NATO-related institutions to the European Union, and rework NATO itself—or even let it lapse.

His analysis identifies East Asia as the “most problematical region” in which to implement restraint, especially with China rising, and he believes that the U.S. has an interest in maintaining a regional balance of power. Yet Posen is not worried about China becoming as big a threat as the Soviets were, and he argues that a Cold War-style approach is unnecessary. Instead, the U.S. should “encourage its allies to assume more responsibility for their own defense,” while maintaining a security-assistance relationship with states like Japan.

In the Middle East, Posen argues that the U.S. should reduce its “salience” in the region in general and in the Israel-Palestine conflict in particular.  This means going “offshore” while maintaining an absolute minimum land presence to keep the oil flowing and prevent any single state from dominating the region. It means the U.S. stays out of the region’s civil wars and focuses on naval power in the Gulf. In the case of Israel, Posen thinks the U.S. should “move deliberately” in reducing its subsidy of Israeli policies that are often not in our interests. To him, this means going back to the America’s pre-1967 Arab-Israeli War position, in which Israel received less military assistance and had to fund its own arms purchases.

In South Asia, Posen advocates moderating U.S. goals while “keeping the pressure on Al-Qaeda on an open-ended basis.” Moderation entails “ratcheting down the U.S. counterinsurgency, nation-building project in Afghanistan,” being more realistic about what can be accomplished there and in Pakistan, and avoiding harming U.S.-Indian relations. (India can be a makeweight to China in Asia.) All this means “moving towards the lowest possible commitment of military force to the region consistent with keeping Al-Qaeda on the defensive.”

In chapter three, Posen describes the military strategy and force structure consistent with restraint. He calls his approach “command of the commons,” which harkens back to the idea of “naval mastery” but with an extension into the domains of air and space.  Such an approach would allow the U.S. to protect its core interests, take advantage of its geostrategic position, incentivize allies to contribute to their security, and buy time in the event of any need to scale up the force. This strategy would naturally place greater relative stress on the Navy and Air Force while allowing sizeable cuts to the Army. Meanwhile, the Marine Corps would refocus on amphibious operations. Overall, restraint would reduce the size and footprint of the military, especially overseas, and shave the cost of defense to about 2.5 percent of GDP (down from over 4 percent in recent years).

Posen ends with a short conclusion that takes on critiques of restraint by advocates of liberal hegemony and by fellow realists. He also discusses paths by which restraint could become reality in U.S. grand strategy.

Restraint is a seminal contribution to the grand strategy debate. It is too bad we cannot guarantee that presidential aspirants and congressional leaders wrestle with its challenge to the prevailing paradigm. Indeed, in an America tired of the burden of empire but with a strong belief in the utility of power, Posen provides a playbook for policymakers who want to appeal to the weary without provoking fear of going soft. He offers a clear path to secure American interests and maintain a robust force able to meet the challenges of the future, while avoiding the entangling commitments and idealistic projects whose costs have weighed so heavily on the nation.

This book’s chief strength is its sober analysis constructed on realist foundations.  Posen sees the world as it is and refuses to let dark nightmares or idealistic dreams lead him astray. Indeed, people in the future are going to look back at the post-Cold War era and wonder why America felt so insecure: nuclear weapons, the world’s strongest Navy and Air Force, and what John Mearsheimer refers to as “the stopping power of water” mean the U.S. is awash in security. Posen’s restraint strategy is one of the few to take all this properly into account. This does not mean that the U.S. is immune to international challenges, particularly from non-state actors. But neither can the U.S. continue to pursue liberal hegemony without paying a significant price to maintain an unnatural unipolar position. Posen’s carefully constructed strategy is tailored to meet the threats and emerging realities of a dynamic world, as well as the U.S. budget crunch.

Posen’s insight into the destabilizing effect of rapid change in international politics shows in his preference for a slow, deliberate transition away from liberal hegemony. But one might be concerned that the U.S.—with an open political system responsive to domestic interest groups—will not be able to stay the course. Given the realities of American politics, it may then be better to err on the side of speed in moving towards restraint.  Either way, for restraint to succeed, it will take a serious commitment by a broad enough swath of the foreign-policy elite to see it through without backsliding. This is going to require educating a new generation of thinkers about the perils of liberal hegemony and the virtues of strategic restraint. The battle of ideas will be critical, and Restraint is a major salvo in that war.  thisarticleappears

One element of the American system that may help restraint is inter-service rivalry in the Department of Defense. If the budget crunch creates a zero-sum game within the military budget fight, restraint will have a natural constituency in the Navy—because of Posen’s “command of the commons” approach—and to a lesser extent in the Air Force. If the Navy brass realize that sweeping budget cuts are inevitable as overall U.S. fiscal realities get uglier, they might rush to embrace restraint, even if they only have institutional interests in mind.

If there is anything in Restraint to quibble with, it is that Posen does not go far enough in reducing unnecessary American commitments in a world very safe for our country. This caution in stepping too far away from the consensus view will probably be its attraction in official debates: it is not a radical, but a reformist grand strategy. Yet it leads down the path to a saner foreign policy, perhaps to one that is even more limited than Posen is willing to admit here. America will be well served if Posen’s restraint emerges as the new hegemon in the national grand strategy debate and charts a course for the 21st century that avoids the mistakes of the past.

William Ruger is is vice president of research and policy at the Charles Koch Institute.