The recent ISIS crisis is Iraq once again has American politicians arguing in favor of military intervention. Among the most vocal are those who led the United States into Iraq a decade ago, a decision that helped set in motion the events now playing out on the outskirts of Baghdad. There will always be such crises and such calls for the United States to deploy its military far beyond its borders.

The problem is that the United States has grown incapable of moderating its ambitions in international politics. Since the collapse of Soviet power, it has pursued a grand strategy that can be called “Liberal Hegemony,” which is unnecessary, counterproductive, costly, and wasteful. In my book, Restraint, I explain why this grand strategy works poorly.

Three major events affected my thinking—the enlargement of NATO to include the former vassal states of the Soviet Union, the war in Kosovo, and the war in Iraq. The first expanded U.S. obligations in ways that did little for U.S. security and needlessly antagonized Russia. Kosovo was an elective war, rationalized on the basis of information that was at best poor, and at worst deliberately mischaracterized by motivated policy entrepreneurs, and nearly bungled militarily due to the war’s founding illusions. The 2003 Iraq war echoed the mistakes of the Kosovo war, but on a larger scale and with much greater costs. Military spending has been excessive throughout this period, because the political ambitions that it serves have been greater than national security required. This is a track record. The United States needs a change of grand strategy.

The United States, like all other countries, must live in the world as it is—a world without a single authority to provide protection. Any state can resort to arms to enforce its claims, so the United States wisely remains prepared to enforce its claims, if it must. The most important claim is to sovereignty, territorial integrity, and safety. That said, the development of military force is expensive, and the use of military force is terrible. Great American generals from William Tecumseh Sherman to Dwight Eisenhower remind us that war is hell and that war is waste. The United States needs military power and needs to be prepared to use it. But this is no casual matter. Military power must be subjected to the discipline of political analysis. That is the purpose of grand strategy.

The United States has the luxury to be very discriminate in the commitments it makes and the wars it fights.

An alternative grand strategy is “Restraint.” Restraint advises us to look first at the elemental strengths of the United States, which make it an easy country to defend. The United States thus has the luxury to be very discriminate in the commitments it makes and the wars it fights. Although the United States has been much at war since the end of the Cold War, only one fight was forced on us—the Afghan War. And even there, the United States was not forced to fight that war in the naïve and profligate fashion that it chose.

The United States is a wealthy and capable state. It can afford more security than most states. But the United States has extended the boundaries of its political and military defense perimeter very far. Taken separately, each individual project has seemed reasonable and affordable, at least to its advocates. Taken together, however, they add up to an embedded system of ambitious and costly excess. For these reasons, I have signed up with the advocates of Restraint. The United States should focus on a small number of threats, and approach those threats with subtlety and moderation. It should do that because the world is resistant to heavy-handed solutions. It can do that because the United States is economically and militarily strong, well-endowed and well-defended by nature, and possessed of an enormous ability to regenerate itself. It is not smart to spend energies transforming a recalcitrant world that we could spend renewing a United States that still needs some work.

Though it may seem inevitable that the United States took the path it did, there was much discussion in the 1990s about how to proceed. One can identify four different strands of opinion. Sadly, these have been reduced to two—the establishment consensus on Liberal Hegemony and Restraint. Four factors helped make Liberal Hegemony the victor. First, with the collapse of Soviet power the United States became the most capable global power in history. Nothing stood in the way. Second, the Western liberal model was triumphant. History vindicated the rightness of our system and made it in our eyes the appropriate model for others. Third, the Cold War ended with U.S. forces “manning the ramparts” around the world. Insecurity and disorder beyond the ramparts quickly created demands from within and without to move them outward. Fourth, the United States had built giant organizations to wage the Cold War and squadrons of national security experts to manage them. Most organization theorists will tell you that organizations never want to go out of business; if they succeed at their first task, they will try to find another. For these reasons, a more rather than a less ambitious strategy emerged after the Cold War, even before the September 11, 2001, terrorist attack on the United States, which supercharged the whole effort.

At bottom, these policies run up against three problems, which will get worse. First, other countries want security as much as we do. When we define our security expansively, we encourage some of them to compete more intensely. Others welcome our help, and because they can count on the United States, are stingy with their own defense spending. They “cheap ride.” Second, global trends will make U.S. expansiveness ever more costly because other states are growing in power, as are peoples and groups, as the U.S. government’s National Intelligence Council has been reporting for several years. More capable states are more able to push back and hence more inclined to do so, as are individuals and nonstate actors. Third, perhaps since the middle of the nineteenth century, ethno-nationalist, religious, and class identities have become heavily politicized. Globalization and modernity have the paradoxical effect of intensifying these identities rather than weakening them. These identities ease the way for the political mobilization of power—for street action, for voting, for civil and international war, for terror. They provide both purpose and motive force. Strong politicized ethno-national and religious identities dislike rule by other groups, or foreigners, above all else. Liberal Hegemony puts the United States in that role, or close to it, too often. Finally, although modern high-technology weaponry has created the impression that military power is a scalpel that can be used to excise diseased politics, in my view it remains a club, which in the end mainly allows us to beat problems into grudging submission at best, remission at worse. Liberal Hegemony is not only unnecessary, it will prove increasingly costly.

There are three important security challenges for the United States—the maintenance of a balance of power in Eurasia, the management of nuclear proliferation, and the suppression of international terrorist organizations that choose the United States as a target.

Restraint dictates that, in Eurasia, the United States would do best to conserve resources by correctly assessing the situation. The European allies are well able to look after themselves, and Russia is no longer a candidate for hegemony. China, on the other hand, may ultimately bid for regional hegemony.  But other states in Asia have considerable capacity to balance China, and rather than rushing the net toward a new "Cold War," the United States should begin to energize these states to make reasonable contributions to their own security.

Zero nuclear proliferation will be difficult to achieve—among other things, it could require costly and ineffective preventive wars.  The United States should do what it can to slow proliferation, and confine possession of nuclear weapons to states that can be deterred because they have something to lose, and keep them out of the hands of independent groups, who may not be deterred because they have little to lose.  This requires much more active cooperation with those states that possess nuclear weapons to ensure the highest standards of control and safety. 

Finally, peculiar terrorist groups with vast ambitions, such as al-Qaeda, will arise from time to time.  Global cooperation to improve defenses and collect intelligence is the best answer.  Wars to secure ungoverned or poorly governed spaces and attempts to build strong democracies have foundered on nationalist resistance to outside forces, and inter-group enmities. Because invasion antagonizes local populations and generates new recruits for terror, kinetic solutions should be used sparingly.

I want to emphasize that the military strategy and structure of Restraint is essentially maritime—“command of the commons.” The United States should invest its scarce military power in the maintenance of an ability to access the rest of the world. It should reduce, however, its regular military presence in the rest of the world. The United States should avoid certain missions altogether, especially coercive state and nation building. Thus the United States can radically cut the ground forces that seem most apt for garrison duties and counterinsurgency. Major force structure cuts should allow the United States to save significant amounts of money, cutting the defense budget to perhaps 2.5 percent of GDP.

Unless the United States begins to recognize the limitations of its power and its resources—as well as the uncertain effects that such decisions can have—it will forever overreach, overspend, and overcommit.

Editors' Note: This article is an updated version of the preface to Barry R. Posen's book, Restraint: A New Foundation for U.S. Grand Strategy. His piece, "The Case for Doing Nothing in Iraq" appeared earlier this month in Politico.

Photograph: U.S. Navy