Courtesy Reuters

PASSING THE BUCK

The central aim of American foreign policy has traditionally been to dominate the western hemisphere while not permitting another great power to dominate Europe or Northeast Asia. The United States has not wanted a peer competitor. In the wake of the Cold War, U.S. policymakers remain firmly committed to this goal. An important Pentagon planning document stated in 1992, "Our first objective is to prevent the reemergence of a new rival ... that poses a threat on the order of that posed formerly by the Soviet Union. ... Our strategy must now refocus on precluding the emergence of any potential future global competitor."

In pursuit of this goal, the United States has behaved as an offshore balancer, committing troops to Europe and Northeast Asia only when there was a potential hegemon in those neighborhoods that the local powers could not contain by themselves. In effect, the United States has followed a "buck-passing" strategy -- remaining on the sidelines while getting others to bear the burden of deterring or fighting aggressors -- until it could no longer do so safely. Unless this realist pattern of behavior changes radically, the future of the U.S. military commitments to Europe and Northeast Asia can thus be expected to hinge on whether a potential hegemon emerges in either region that can be contained only with American help. If not, the more than 100,000 U.S. troops based in each region will probably leave in the first decade or so of the new century.

Europe and Northeast Asia are stable and peaceful today. Many attribute this quiescence to regional integration, or democracy, or the replacement of militaristic strategic cultures with pacific ones. In fact, however, the current peace and stability are based largely on auspicious distributions of power that make war highly unlikely.

But if the power structures that are now in place in Europe and Northeast Asia are benign, they are not sustainable for much longer. The most likely scenario in Europe is an eventual American exit coupled with the emergence of Germany as the dominant state. In effect, the region will probably move from its present bipolarity (with the United States and Russia as the poles) to unbalanced multipolarity, which will lead to more intense security competition among the European powers.

The evolution of the power structure in Northeast Asia, meanwhile, will depend on whether China's rise continues. If China does not become a potential hegemon, the United States is likely to pull its troops out of the area, thereby encouraging Japan to build up its military capability and become a great power once again. The regional system would remain multipolar and balanced, but security competition would be somewhat more intense than it is today.

If China does emerge as a potential hegemon, however, Northeast Asia will fall into unbalanced multipolarity and the United States will move to contain the Chinese threat. Because China has such vast latent power potential (due to the size of its economy and its population), this last scenario is clearly the most dangerous for the United States, and American foreign policy elites are trying hard to head it off -- by engaging China in the hope that, as it becomes more prosperous and democratic, its demands and behavior will moderate, and by keeping large numbers of troops deployed in Northeast Asia in an attempt to prevent conflicts from starting. Yet both of these policies are misguided. U.S. interests would be best served by slowing Chinese growth rather than accelerating it, and by pulling American troops back so that they can stay out of future wars -- or at least join them later rather than earlier.

THE SHERIFF LEAVES TOWN

hardly any evidence before 1990 suggests that Washington is willing to commit troops to Europe or Northeast Asia except to block the imminent rise of a peer competitor. One might concede this history but argue that the more relevant evidence is what has happened over the last decade. It is true that during the 1990s substantial numbers of American troops remained abroad even though no great power threatened to dominate Europe or Northeast Asia. Too little time has passed since the Cold War ended, however, to make a judgment about whether U.S. forces will stay put for long in the absence of the Soviet threat or its equivalent.

The Soviet Union broke apart at the end of 1991, only ten years ago, and the last Russian troops were removed from the former East Germany in 1994, a mere seven years ago. Given the suddenness of the Soviet collapse and its profound effect on the balance of power in Europe and Northeast Asia, the United States has needed time to figure out what these changes mean for American interests. By way of comparison, World War I ended in 1918, but U.S. troops were not completely withdrawn from Europe until 1923, and British troops remained on the continent until 1930 -- 12 years after the fighting stopped.

Simple inertia has also been an important factor in delaying the American withdrawal. The United States has maintained large-scale military forces in Europe since 1943, when it invaded Italy during World War II, and in Northeast Asia since 1945, when it occupied Japan at the end of that war. Both NATO and the American alliance structure in Northeast Asia are institutions with deep roots that helped win a spectacular victory in the Cold War, and the United States could not walk away from them overnight. Furthermore, maintaining forces in Europe and Northeast Asia in the past decade has been relatively cheap and painless. Not only has the American economy flourished during this period, generating large budget surpluses in the process, but China and Russia have been easy to contain, because they have been much weaker than the United States.

There is considerable evidence, however, that the United States and its Cold War allies are now beginning to drift apart. This trend is most apparent in Europe, where NATO's 1999 war against Serbia and its messy aftermath have damaged transatlantic relations and prompted the European Union to begin building a military force of its own that can operate independently of NATO -- meaning the United States. The United Kingdom, France, Germany, and Italy are slowly but inexorably realizing that they want to provide for their own security and control their own destiny. They are less willing to take orders from the United States than they were during the Cold War. Japan, too, is showing signs of independent behavior. And the U.S. commitment to defend Europe and Northeast Asia is weakening. Public opinion polls and congressional sentiment seem to indicate that the United States has become, at best, what one commentator has called a "reluctant sheriff" on the world stage. Over time, therefore, the U.S. military role abroad is likely to diminish, not increase.

Given that the United States is widely recognized to be a pacifying force in Europe and Northeast Asia, one might wonder why its allies would assert their independence from the United States, a move that is almost certain to cause transatlantic friction. Some might say that this is evidence that Washington's former allies are now trying to balance the mighty United States. But that response is not convincing, because the United States has no appetite for conquest and domination outside of the western hemisphere. Offshore balancers do not provoke balancing coalitions against themselves; indeed, their main mission is to help balance against others.

America's Cold War allies have started to act less like dependents and more like sovereign states because -- being perhaps more perceptive than Washington's own foreign policy elites -- they fear that the offshore balancer that has protected them for so long might prove to be unreliable in a future crisis. The reliability of the United States was not a serious problem during the Cold War, because the Soviet threat provided a powerful incentive for the United States to protect its allies, who were too weak to defend themselves. The absence of that threat, however, has led America's allies to question how long the United States will take its commitment to their security seriously. Moreover, it has created a situation in which states such as Germany and Japan have the option of trying to protect themselves without American help.

The United States is also bound to raise doubts about whether it is a wise and reliable ally thanks to the policies it pursues, if only because U.S. interests are not identical to those of its friends. For example, President Bill Clinton, hoping to improve Sino-American relations, visited China for nine days in 1998 without stopping in Japan. His itinerary was seen by Japanese leaders as evidence that their alliance with the United States was weakening. In Europe, the ongoing Balkan crises have raised doubts about American leadership. The United States and its European allies, moreover, have conflicting views about Middle East policy, about employing NATO forces outside of Europe, and especially about developing a national missile defense. Over time, differences of this sort are likely to cause America's allies to provide for their own security, rather than rely on the United States.

In sum, the brief history of the 1990s is not a good indicator of what the future holds for U.S. military involvement in Europe and Northeast Asia. That issue will likely be resolved in the early years of the current century, and the determining factor will be whether a potential hegemon emerges in either region that the United States must help contain. Only the threat of a peer competitor is likely to provide sufficient incentive for the United States to risk involvement in a distant great-power war.

EUROPE'S FUTURE

Five European states now have sufficient wealth and population to qualify as potential great powers: the United Kingdom, France, Germany, Italy, and Russia. Of these, however, only Germany has the earmarks of a potential hegemon. It is the wealthiest European state, has the second-largest population (after Russia), and has the most powerful army in the region. Nevertheless, Germany is not a great power today, much less a potential hegemon, because it has no nuclear weapons of its own and because it is heavily dependent on the United States for its security. If American troops were pulled out of Europe, however, and Germany became responsible for its own defense, it would probably acquire its own nuclear arsenal and increase the size of its army, transforming itself into something much more formidable.

To illustrate Germany's potential military might, consider the population and wealth differentials between Germany and Russia during the twentieth century. Although Russia has always enjoyed a significant population advantage over Germany, its present edge is smaller than at any other time in the past hundred years. For example, Russia had approximately 2.6 times as many people as Germany in 1913 (175 million vs. 67 million), and twice as many in 1940 (170 million vs. 85 million). Despite this population disadvantage, Germany was a potential hegemon in both those years because of its marked advantage in wealth. It had a roughly 3.6-to-1 advantage in industrial might over Russia in 1913, and a 1.3-to-1 advantage in 1940.

Over the last 15 years, the balance has shifted quite rapidly in Germany's favor, bringing it back to a very powerful position. In 1987, a representative year of the Cold War, the Soviet Union had roughly 4.7 times as many people as did West Germany (285 million vs. 61 million). Russia today, however, has only about 1.8 times as many people as Germany (147 million vs. 82 million), and Germany has a startling 6.6-to-1 advantage in wealth. Thus Germany now has a significant advantage in latent power over Russia, much like it had in the early twentieth century, when it was the dominant power in Europe.

Germany also has an advantage in conventional military power. The size of Germany's standing army is 221,100 soldiers, and it can be quickly augmented by 295,400 reserves, thus creating a highly effective fighting force of more than half a million soldiers. Russia has about 348,000 soldiers in its standing army, and although it has a large pool of reserves, they are poorly trained and hard to mobilize quickly and efficiently in a crisis. In terms of quality, the German army is well trained and well led, whereas the Russian army is neither. Only on the nuclear front does Russia dominate, but Germany has the wherewithal to rectify this asymmetry if it chooses to.

Yet even though Germany is likely to become a potential hegemon if it has to provide for its own security, the United States is still likely to pull its forces out of Europe. Why? Because despite Germany's significant military potential, other European powers should be able to keep it from dominating Europe without help from the United States. The United Kingdom, France, Italy, and Russia together have about three times as many people as Germany does, and their combined wealth is roughly three times greater than Germany's. The United Kingdom, France, and Russia all have nuclear weapons, moreover, providing a strong deterrent against an expansionist Germany even if it does develop its own nuclear option.

Without the American pacifier, Europe is not guaranteed to remain peaceful. Indeed, intense security competition among the great powers would likely ensue because, upon American withdrawal, Europe would go from benign bipolarity to unbalanced multipolarity, the most dangerous kind of power structure. The United Kingdom, France, Italy, and Germany would have to build up their own military forces and provide for their own security. In effect, they would all become great powers, making Europe multipolar and raising the ever-present possibility that they might fight among themselves. And Germany would probably become a potential hegemon and thus the main source of worry.

Looking at Europe today, such a forecast might appear far-fetched, but that is because few are prepared to consider how radically the European security environment will be transformed by the withdrawal of U.S. troops. Once the major European powers are forced to provide for their own defense, suspicions among them are certain to grow, thereby triggering the familiar dynamics of great-power competition.

The kind of trouble that might lie ahead for Europe can be illustrated by considering how particular German measures aimed at enhancing its security might nevertheless lead to instability. If the United States removed its security umbrella from over western Europe, Germany would likely move to acquire its own nuclear arsenal. This would be the case both because nuclear weapons are an excellent deterrent, as Germany's governing elites recognized during the Cold War, but also because it would be the best way to escape potential coercion by its three nuclear-armed neighbors. During the proliferation process, however, these neighbors would probably contemplate using force to prevent Germany from going nuclear, and the result could be a major crisis.

Without the American military on its territory, furthermore, Germany would probably increase the size of its army and certainly would be more inclined to try to dominate central Europe. Why? Because Germany would fear Russian control of that critically important buffer zone between them. Of course, Russia would have the same fear in reverse, which would likely lead to a serious security competition between them for control of central Europe. France, meanwhile, would undoubtedly view such behavior by Germany with alarm and take measures to protect itself -- for example, by increasing its defense spending and establishing closer relations with Russia. Germany, of course, would perceive these actions as hostile and respond with measures of its own.

Depending on what happens with Russia, however, Europe's future could turn out differently. It is conceivable, although unlikely, that Russia, rather than Germany, will become Europe's next potential hegemon. For this to happen, Russia would need to match its large population with greater wealth. Although it is hard to imagine this happening over the next 20 years, if it did so the other European powers would probably be able to contain the potential Russian threat on their own. A wealthy Russia would not be a paper tiger, but it would not be so formidable that U.S. troops would be needed to contain it.

Russia could also go in the other direction: its economy could collapse, possibly causing severe political turmoil, and the country could effectively be removed from the ranks of the great powers. But in this event, the other European powers would not be strong enough to contain Germany on their own, and would need help from the United States. This alternative future is not likely to come about either, but if it did, U.S. troops would surely remain in Europe to help the United Kingdom, France, and Italy check German expansion.

CHINA'S CHALLENGE

Three Northeast Asian states -- China, Japan, and Russia -- presently have sufficient population and wealth to qualify as potential great powers, but at the moment none is a potential hegemon. Japan is by far the wealthiest state in the region. Its GNP is about 3.5 times as large as China's and more than 12 times as large as Russia's. Nevertheless, Japan is not in a position to convert its substantial wealth into a decisive military advantage that could be used to threaten the rest of Northeast Asia, for two reasons.

First, although Japan is now much richer than either China or Russia, its population is relatively small -- about one-tenth the size of China's, with the gap likely to widen even further over the next 50 years. It would thus be almost impossible for Japan to build an army more powerful than China's. It could certainly build an army that is qualitatively superior, but not so much better that it would offset the numerical advantage that China could maintain because of its huge population. Second, if Japan tried to overrun Northeast Asia, it would also face a serious power-projection problem. It is an insular state that is physically separated from the Asian mainland by a substantial body of water. Thus, unless Japan could secure a foothold on the Asian continent -- which would be unlikely -- it would have to invade from the sea to conquer it. Japan had little difficulty invading and maintaining a large army on the continent when it chose to between 1895 and 1945, because China and Korea were both so weak. But today China and Korea are much more formidable adversaries, and they would surely use their armies to oppose a Japanese invasion of the Asian mainland. Amphibious operations against territory controlled by China and Korea would be a daunting task. In short, if Japan shakes loose the United States and becomes a great power in the next decade or so, it is more likely to resemble the United Kingdom in the mid-nineteenth century than Japan in the first half of the twentieth century.

Russia also has little chance of dominating Northeast Asia over the next two decades. It is hard to imagine Russia building an economy more powerful than Japan's any time soon. But even if Russia were to experience spectacular economic growth, it would still face essentially the same population problem vis-ˆ-vis China that Japan does. China has more than eight times as many people as Russia and the gap between them is likely to widen. Thus not even a wealthy Russia could field an army more powerful than China's. And Russia also has significant security concerns in Europe and on its southern borders, which limit the military resources it can devote to Northeast Asia.

The key to understanding the future distribution of power in Northeast Asia, therefore, is China. It is clearly not a potential hegemon today, because it is not nearly as wealthy as Japan. But if China's economy continues expanding over the next two decades at or near the rate it has been since the early 1980s, China will likely surpass Japan as the wealthiest state in the region. And because of its vast population, China has the potential to become even richer than the United States in the long term.

China's potential wealth and power can be illustrated in the following way. Right now, Japan has a population one-tenth the size of China's and a per capita GNP ($32,350) that is 40 times greater. If China modernizes to the point where it has about the same per capita GNP as South Korea does today ($8,600), it will have an economy 2.5 times the size of Japan's current one and 1.3 times the size of the U.S. economy. And if China achieves a per capita GNP equal to about half that of Japan, its economy will be 5 times larger than Japan's and 2.5 times larger than that of the United States. For most of the Cold War, it should be remembered, the Soviet economy was only about half the size of the American economy.

It is difficult to predict where the Chinese economy is headed, and thus whether China will overtake Japan and become a potential hegemon in Northeast Asia during the next few decades. Nonetheless, the principal ingredients of military power in that region are likely to be distributed in one of two ways. The first scenario would emerge if China's economy stops growing rapidly and Japan remains the wealthiest state in the region. In these circumstances, neither would become a potential hegemon and the United States would likely bring its troops home. Japan would then almost surely establish itself as a great power, building its own nuclear deterrent and significantly increasing the size of its conventional forces. But there would still be balance in the region: Japan would replace the United States, and China and Russia would remain the region's other great powers. In short, an American exit would not change the basic regional power structure, and presumably would not make major war there more or less likely than it is today.

Substituting Japan for the United States would, however, increase the likelihood of regional instability. Whereas the United States has a robust nuclear deterrent that contributes to peace, Japan would have to build its own. That process, however, would be fraught with dangers, because China and perhaps Russia would be tempted to use force to prevent the emergence of a nuclear-armed Japan. The deep-seated fear of Japan in Asia that is a legacy of its behavior between 1895 and 1945, moreover, would surely be fanned if Japan acquired a nuclear deterrent, intensifying security competition in the region. And even though Japan would face profound limits on its ability to project power onto the Asian mainland so long as China remained a great power, it still has potentially troublesome territorial disputes with the mainland powers -- with China over the Senkakuff/Diaoyutai Islands, with South Korea over the Takeshima/Tokto Islets, and with Russia over the Kuriles. Finally, although China is militarily too weak to fight a major war with the mighty United States, it is not likely to be as outgunned by Japan, which simply does not have the population or the wealth to fully replace U.S. military power.

The second scenario would emerge if China's economy continues growing at a robust pace. This would eventually enable it to become a potential regional hegemon, leading the United States to remain in Northeast Asia -- or return to it if it had left -- in order to prevent China from becoming a global peer competitor. This would be necessary because China would be too strong to be contained by Japan and Russia, even if they got help from India, South Korea, and Vietnam. Not only would China be much wealthier than any of its Asian rivals in this scenario, but its huge population advantage would allow it to build an army far more powerful than that of either Japan or Russia and to acquire an impressive nuclear arsenal. As a result, Northeast Asia would be a dramatically unbalanced multipolar system, and thus a much more dangerous place than it is now. Like all previous potential hegemons, China would be strongly inclined to translate its potential influence into reality, and all of its rivals, including the United States, would encircle it to try to keep it from expanding.

ANALYTICAL INCORRECTNESS

The implications of this analysis for the future of American national security policy are clear. The most dangerous scenario the United States might face in the early twenty-first century is one in which China becomes a potential hegemon in Northeast Asia. Of course, China's prospects of doing so depend largely on whether its economy continues modernizing at a rapid pace. If that happens, and China becomes not only a leading producer of cutting-edge technologies but also the world's wealthiest great power, it would almost certainly use its wealth to build a mighty military machine. For sound strategic reasons, moreover, it would surely pursue regional hegemony, just as the United States did in the western hemisphere during the nineteenth century. So if Chinese relative power grows substantially, one should expect it to attempt to dominate Japan and South Korea, as well as other regional actors, by building military forces that are so powerful that those other states would not dare challenge it. One should also expect it to develop its own version of the Monroe Doctrine, directed at the United States; just as the United States has made it clear to distant great powers that they are not allowed to meddle in the western hemisphere, China will make it clear that American interference in Asia is unacceptable.

What makes a future Chinese threat so worrisome is that it might be far more powerful and dangerous than any of the potential hegemons that the United States confronted during the twentieth century. Neither Wilhelmine Germany, nor imperial Japan, nor Nazi Germany, nor the Soviet Union had nearly as much latent power as the United States did during their confrontations. But if China were to become a giant Hong Kong, it would eventually have several times as much latent power as the United States, allowing it to gain a decisive military advantage in Northeast Asia. In that situation, it is hard to see how the United States could prevent China from becoming a peer competitor, or even from eventually becoming a more formidable superpower.

This analysis suggests that the United States has a profound interest in seeing Chinese economic growth slow considerably in the years ahead. For much of the last decade, however, the United States has pursued a strategy intended to have the opposite effect. The United States has been committed to engaging China rather than containing it. Constructive engagement is predicated on the liberal belief that if China could be made both democratic and prosperous, it would become a status quo power and not engage in security competition with the United States. As a result, U.S. policy has sought to integrate China into the world economy and facilitate its rapid economic development, so that it becomes wealthy and content with its position in the international system.

This approach is misguided, however, because a wealthy China would not be a status quo power; it would be an aggressive one determined to achieve regional hegemony -- not because a rich China would have wicked motives, but because the best way for any state to maximize its prospects for survival is to dominate its region of the world. Although it is certainly in China's interest to be the hegemon in Northeast Asia, it is clearly not in the interest of the United States to have that happen.

At the same time that it is building up rather than placing obstacles in the way of its greatest potential rival, the United States is also exposing itself to trouble rather than taking sensible precautions in advance of future conflict. Many in the U.S. foreign policy elite today dismiss the buck-passing strategy that has served the nation well in the past. Rather than dispatching troops only to head off an imminent danger from an unchecked potential hegemon, they offer a different rationale for maintaining a robust U.S. military presence abroad. The United States, they argue, has a deep-seated interest in maintaining peace in Europe and Northeast Asia, and its troops have to stay there because bringing them home would probably lead to instability and maybe even great-power war.

Peace in these regions, according to the current conventional wisdom, is of vital importance to the United States for both economic and security reasons. A major war in either area would undermine American economic prosperity. Given the high levels of economic interdependence among the world's wealthiest powers, even if the United States managed to stay out of the fighting, a great-power war would badly damage America's economy as well as those of the warring states. Since the United States invariably gets dragged into distant great-power wars, moreover, Americans are deluding themselves if they think they can sit out a major conflict in either Europe or Northeast Asia. To avoid having large numbers of Americans die down the road, therefore, the United States should maintain forces in those regions and preserve the peace, now and for the foreseeable future.

This conventional wisdom is seriously flawed. There is indeed little doubt that peace in Europe and Northeast Asia is a desirable goal for the United States. The key issue, however, is whether peace is important enough to justify putting U.S. troops in harm's way, which is the risk the United States runs if it stations forces in those regions indefinitely. In fact, although peace in these two wealthy regions is an important U.S. interest, it is not a vital one. The rationale for thinking otherwise is unconvincing and receives little support from the historical record.

Consider the claim that a war in Europe or Northeast Asia would undermine American prosperity, which is generally based on assertion, not analysis. The only study that I know of on the subject, by political scientists Eugene Gholz and Daryl Press, contradicts that claim. It concludes that "the primary effect of overseas wars on the economies of neutral countries is to redistribute wealth from belligerents to non-combatants, enriching neutrals rather than impoverishing them." In essence, in the event of an Asian or a European war the United States would not only probably become more prosperous in absolute terms, it would also gain relative power over the warring states. This is what happened to the United States when it was neutral for much of World War I: after some initial problems, the American economy flourished, while the economies of the European great powers were badly damaged. There is little reason to think that a major war in Europe or Northeast Asia today would seriously damage the U.S. economy, since, as Gholz and Press note, the U.S. economy is "roughly as vulnerable to a major great power war in Asia as it was to World War I, but it is only half as vulnerable today to disruptions in Europe as it was early in the 20th Century."

Even if this analysis is wrong, however, and a major war in Europe or Northeast Asia would make Americans less prosperous, the United States would still be unlikely to fight just to ensure continued economic prosperity. Two prominent cases in recent times support this point. The United States did not use, or even seriously consider using, military force against any of the members of the Organization of Petroleum Exporting Countries during the oil crisis of the mid-1970s, even though OPEC's actions at the time undermined American prosperity. Furthermore, in the fall of 1990, the administration of President George H.W. Bush briefly tried to justify the impending Persian Gulf War on the grounds that Iraq's invasion of Kuwait had to be reversed because it threatened American jobs. This argument was heavily criticized and quickly abandoned. If the United States was unwilling to fight a war against weak oil-producing states for the sake of economic prosperity, it is hard to imagine it engaging in a great-power war for the same purpose.

The claim that the United States invariably gets drawn into great-power wars in Europe is also not persuasive. Both the United Kingdom and the United States have traditionally been offshore balancers who have been pulled into great-power conflicts only when there has been a potential regional hegemon that other parties could not contain by themselves. For example, both the United Kingdom and the United States were content to sit out the Franco-Prussian War (1870-71) and the Russo-Japanese War (1904-5), because in neither case did the outcome threaten to create a hegemonic power. Moreover, the United States would not have entered World War I or World War II had the European powers been able to contain Germany by themselves. It was only because Germany threatened to overrun Europe in early 1917 and again in mid-1940 that the United States accepted a continental commitment.

One might counter that if the United States stays put in Europe and Northeast Asia, there will be no great-power war in the first place and thus no danger that Americans might have to suffer its horrible costs. But although a U.S. military presence may make war less likely, it cannot guarantee that conflict will not break out. If the U.S. military stays put in Northeast Asia, for example, it could plausibly end up in a war with China over Taiwan. If a great-power war does occur, moreover, this time the United States will be involved from the start, which does not make good strategic sense. It would be best for the United States either to avoid the fighting entirely or, if it has to join in, to do so later rather than earlier. That way, the United States would pay a much smaller price than the states fighting from start to finish and would be well positioned at the war's end to win the peace and shape the postwar world to its advantage.

China is still far away from having enough latent power to make a run at regional hegemony, so it is not too late for the United States to reverse course and do what it can to slow China's rise. And the current U.S. military commitments to Europe and Northeast Asia are hardly set in stone -- as America's allies in those regions understand all too well. The powerful structural imperatives of the international system, in fact, will probably force the United States to abandon its policy of constructive engagement in the near future and bring its troops home if there is no immediate threat for them to counter. But states occasionally ignore signals from the anarchic world in which they operate, choosing instead to pursue strategies that contradict straightforward balance-of-power logic. The United States is a good candidate for behaving in that way, because American political culture is deeply liberal and correspondingly hostile to realist ideas. It would be a grave mistake, however, for the country to turn its back on the realist principles that have served it well since its founding.

  • John J. Mearsheimer is R. Wendell Harrison Distinguished Service Professor of Political Science at the University of Chicago. This article is adapted from his forthcoming book The Tragedy of Great Power Politics.
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