作者：斯蒂芬·沃尔特（Stephen M. Walt）2011年10月25日 The National Interest
THE UNITED States has been the dominant world power since 1945, and U.S. leaders have long sought to preserve that privileged position. They understood, as did most Americans, that primacy brought important benefits. It made other states less likely to threaten America or its vital interests directly. By dampening great-power competition and giving Washington the capacity to shape regional balances of power, primacy contributed to a more tranquil international environment. That tranquility fostered global prosperity; investors and traders operate with greater confidence when there is less danger of war. Primacy also gave the United States the ability to work for positive ends: promoting human rights and slowing the spread of weapons of mass destruction. It may be lonely at the top, but Americans have found the view compelling.
When a state stands alone at the pinnacle of power, however, there is nowhere to go but down. And so Americans have repeatedly worried about the possibility of decline—even when the prospect was remote. Back in 1950, National Security Council Report 68 warned that Soviet acquisition of atomic weapons heralded an irreversible shift in geopolitical momentum in Moscow’s favor. A few years later, Sputnik’s launch led many to fear that Soviet premier Nikita S. Khrushchev’s pledge to “bury” Western capitalism might just come true. President John F. Kennedy reportedly believed the USSR would eventually be wealthier than the United States, and Richard Nixon famously opined that America was becoming a “pitiful, helpless giant.” Over the next decade or so, defeat in Indochina and persistent economic problems led prominent academics to produce books with titles like America as an Ordinary Country and After Hegemony.1 Far-fetched concerns about Soviet dominance helped propel Ronald Reagan to the presidency and were used to justify a major military buildup in the early 1980s. The fear of imminent decline, it seems, has been with us ever since the United States reached the zenith of global power.
Debates about decline took on new life with the publication of Paul Kennedy’s best-selling Rise and Fall of the Great Powers, which famously argued that America was in danger of “imperial overstretch.” Kennedy believed Great Britain returned to the unseemly ranks of mediocrity because it spent too much money defending far-flung interests and fighting costly wars, and he warned that the United States was headed down a similar path. Joseph Nye challenged Kennedy’s pessimism in Bound to Lead: The Changing Nature of American Power, which sold fewer copies but offered a more accurate near-term forecast. Nye emphasized America’s unusual strengths, arguing it was destined to be the leading world power for many years to come.
Since then, a host of books and articles—from Charles Krauthammer’s “The Unipolar Moment,” G. John Ikenberry’s Liberal Leviathan and Niall Ferguson’s Colossus to Fareed Zakaria’s The Post-American World (to name but a few)—have debated how long American dominance could possibly last. Even Osama bin Laden eventually got in on the act, proclaiming the wars in Iraq and Afghanistan fatal blows to American power and a vindication of al-Qaeda’s campaign of terror.
Yet for all the ink that has been spilled on the durability of American primacy, the protagonists have mostly asked the wrong question. The issue has never been whether the United States was about to imitate Britain’s fall from the ranks of the great powers or suffer some other form of catastrophic decline. The real question was always whether what one might term the “American Era”was nearing its end. Specifically, might the United States remain the strongest global power but be unable to exercise the same influence it once enjoyed? If that is the case—and I believe it is—then Washington must devise a grand strategy that acknowledges this new reality but still uses America’s enduring assets to advance the national interest.
THE AMERICAN Era began immediately after World War II. Europe may have been the center of international politics for over three centuries, but two destructive world wars decimated these great powers. The State Department’s Policy Planning Staff declared in 1947 that “preponderant power must be the object of U.S. policy,” and its willingness to openly acknowledge this goal speaks volumes about the imbalance of power in America’s favor. International-relations scholars commonly speak of this moment as a transition from a multipolar to a bipolar world, but Cold War bipolarity was decidedly lopsided from the start.
In 1945, for example, the U.S. economy produced roughly half of gross world product, and the United States was a major creditor nation with a positive trade balance. It had the world’s largest navy and air force, an industrial base second to none, sole possession of atomic weapons and a globe-circling array of military bases. By supporting decolonization and backing European reconstruction through the Marshall Plan, Washington also enjoyed considerable goodwill in most of the developed and developing world.
Most importantly, the United States was in a remarkably favorable geopolitical position. There were no other great powers in the Western Hemisphere, so Americans did not have to worry about foreign invasion. Our Soviet rival had a much smaller and less efficient economy. Its military might, concentrated on ground forces, never approached the global reach of U.S. power-projection capabilities. The other major power centers were all located on or near the Eurasian landmass—close to the Soviet Union and far from the United States—which made even former rivals like Germany and Japan eager for U.S. protection from the Russian bear. Thus, as the Cold War proceeded, the United States amassed a strong and loyal set of allies while the USSR led an alliance of comparatively weak and reluctant partners. In short, even before the Soviet Union collapsed, America’s overall position was about as favorable as any great power’s in modern history.
What did the United States do with these impressive advantages? In the decades after World War II, it created and led a political, security and economic order in virtually every part of the globe, except for the sphere that was directly controlled by the Soviet Union and its Communist clients. Not only did the United States bring most of the world into institutions that were largely made in America (the UN, the World Bank, the IMF, and the General Agreement on Tariffs and Trade), for decades it retained the dominant influence in these arrangements.
In Europe, the Marshall Plan revitalized local economies, covert U.S. intervention helped ensure that Communist parties did not gain power, and NATO secured the peace and deterred Soviet military pressure. The position of supreme allied commander was always reserved for a U.S. officer, and no significant European security initiative took place without American support and approval. (The main exception, which supports the general point, was the ill-fated Anglo-French-Israeli attack on Egypt during the Suez crisis of 1956, an adventure that collapsed in the face of strong U.S. opposition.) The United States built an equally durable security order in Asia through bilateral treaties with Japan, South Korea, Australia, New Zealand, the Philippines and several others, and it incorporated each of these countries into an increasingly liberal world economy. In the Middle East, Washington helped establish and defend Israel but also forged close security ties with Saudi Arabia, Jordan, the shah of Iran and several smaller Gulf states. America continued to exercise a position of hegemony in the Western Hemisphere, using various tools to oust leftist governments in Guatemala, the Dominican Republic, Chile and Nicaragua. In Africa, not seen as a vital arena, America did just enough to ensure that its modest interests there were protected.
To be sure, the United States did not exert total control over events in the various regional orders it created. It could not prevent the revolution in Cuba in 1959 or Iran in 1979, it failed to keep France from leaving NATO’s integrated military command structure in 1966, and it did not stop Israel, India, North Korea and Pakistan from acquiring nuclear weapons. But the United States retained enormous influence in each of these regions, especially on major issues.
Furthermore, although the U.S. position was sometimes challenged—the loss in Vietnam being the most obvious example—America’s overall standing was never in danger. The U.S. alliance system in Asia held firm despite defeat in Indochina, and during the 1970s, Beijing formed a tacit partnership with Washington. Moreover, China eventually abandoned Marxism-Leninism as a governing ideology, forswore world revolution and voluntarily entered the structure of institutions that the United States had previously created. Similarly, Tehran became an adversary once the clerical regime took over, but America’s overall position in the Middle East was not shaken. Oil continued to flow out of the Persian Gulf, Israel became increasingly secure and prosperous, and key Soviet allies like Egypt eventually abandoned Moscow and sided with the United States. Despite occasional setbacks, the essential features of the American Era remained firmly in place.
Needless to say, it is highly unusual for a country with only 5 percent of the world’s population to be able to organize favorable political, economic and security orders in almost every corner of the globe and to sustain them for decades. Yet that is in fact what the United States did from 1945 to 1990. And it did so while enjoying a half century of economic growth that was nearly unmatched in modern history.
And then the Soviet empire collapsed, leaving the United States as the sole superpower in a unipolar world. According to former national-security adviser Brent Scowcroft, the United States found itself “standing alone at the height of power. It was, it is, an unparalleled situation in history, one which presents us with the rarest opportunity to shape the world.” And so it tried, bringing most of the Warsaw Pact into NATO and encouraging the spread of market economies and democratic institutions throughout the former Communist world. It was a triumphal moment—the apogee of the American Era—but the celebratory fireworks blinded us to the trends and pitfalls that brought that era to an end.
THE PAST two decades have witnessed the emergence of new power centers in several key regions. The most obvious example is China, whose explosive economic growth is undoubtedly the most significant geopolitical development in decades. The United States has been the world’s largest economy since roughly 1900, but China is likely to overtake America in total economic output no later than 2025. Beijing’s military budget is rising by roughly 10 percent per year, and it is likely to convert even more of its wealth into military assets in the future. If China is like all previous great powers—including the United States—its definition of “vital” interests will grow as its power increases—and it will try to use its growing muscle to protect an expanding sphere of influence. Given its dependence on raw-material imports (especially energy) and export-led growth, prudent Chinese leaders will want to make sure that no one is in a position to deny them access to the resources and markets on which their future prosperity and political stability depend.
This situation will encourage Beijing to challenge the current U.S. role in Asia. Such ambitions should not be hard for Americans to understand, given that the United States has sought to exclude outside powers from its own neighborhood ever since the Monroe Doctrine. By a similar logic, China is bound to feel uneasy if Washington maintains a network of Asian alliances and a sizable military presence in East Asia and the Indian Ocean. Over time, Beijing will try to convince other Asian states to abandon ties with America, and Washington will almost certainly resist these efforts. An intense security competition will follow.
The security arrangements that defined the American Era are also being undermined by the rise of several key regional powers, most notably India, Turkey and Brazil. Each of these states has achieved impressive economic growth over the past decade, and each has become more willing to chart its own course independent of Washington’s wishes. None of them are on the verge of becoming true global powers—Brazil’s GDP is still less than one-sixth that of the United States, and India and Turkey’s economies are even smaller—but each has become increasingly influential within its own region. This gradual diffusion of power is also seen in the recent expansion of the G-8 into the so-called G-20, a tacit recognition that the global institutions created after World War II are increasingly obsolete and in need of reform.
Each of these new regional powers is a democracy, which means that its leaders pay close attention to public opinion. As a result, the United States can no longer rely on cozy relations with privileged elites or military juntas. When only 10–15 percent of Turkish citizens have a “favorable” view of America, it becomes easier to understand why Ankara refused to let Washington use its territory to attack Iraq in 2003 and why Turkey has curtailed its previously close ties with Israel despite repeated U.S. efforts to heal the rift. Anti-Americanism is less prevalent in Brazil and India, but their democratically elected leaders are hardly deferential to Washington either.
The rise of new powers is bringing the short-lived “unipolar moment” to an end, and the result will be either a bipolar Sino-American rivalry or a multipolar system containing several unequal great powers. The United States is likely to remain the strongest, but its overall lead has shrunk—and it is shrinking further still.
Of course, the twin debacles in Iraq and Afghanistan only served to accelerate the waning of American dominance and underscore the limits of U.S. power. The Iraq War alone will carry a price tag of more than $3 trillion once all the costs are counted, and the end result is likely to be an unstable quasi democracy that is openly hostile to Israel and at least partly aligned with Iran. Indeed, Tehran has been the main beneficiary of this ill-conceived adventure, which is surely not what the Bush administration had in mind when it dragged the country to war.
The long Afghan campaign is even more likely to end badly, even if U.S. leaders eventually try to spin it as some sort of victory. The Obama administration finally got Osama bin Laden, but the long and costly attempt to eliminate the Taliban and build a Western-style state in Afghanistan has failed. At this point, the only interesting question is whether the United States will get out quickly or get out slowly. In either scenario, Kabul’s fate will ultimately be determined by the Afghans once the United States and its dwindling set of allies leave. And if failure in Afghanistan weren’t enough, U.S. involvement in Central Asia has undermined relations with nuclear-armed Pakistan and reinforced virulent anti-Americanism in that troubled country. If victory is defined as achieving your main objectives and ending a war with your security and prosperity enhanced, then both of these conflicts must be counted as expensive defeats.
But the Iraq and Afghan wars were not simply costly self-inflicted wounds; they were also eloquent demonstrations of the limits of military power. There was never much doubt that the United States could topple relatively weak and/or unpopular governments—as it has in Panama, Afghanistan, Iraq and, most recently, Libya—but the wars in Iraq and Afghanistan showed that unmatched power-projection capabilities were of little use in constructing effective political orders once the offending leadership was removed. In places where local identities remain strong and foreign interference is not welcome for long, even a global superpower like the United States has trouble obtaining desirable political results.
Nowhere is this clearer than in the greater Middle East, which has been the main focus of U.S. strategy since the USSR broke apart. Not only did the Arab Spring catch Washington by surprise, but the U.S. response further revealed its diminished capacity to shape events in its favor. After briefly trying to shore up the Mubarak regime, the Obama administration realigned itself with the forces challenging the existing regional order. The president gave a typically eloquent speech endorsing change, but nobody in the region paid much attention. Indeed, with the partial exception of Libya, U.S. influence over the entire process has been modest at best. Obama was unable to stop Saudi Arabia from sending troops to Bahrain—where Riyadh helped to quell demands for reform—or to convince Syrian leader Bashar al-Assad to step down. U.S. leverage in the post-Mubarak political process in Egypt and the simmering conflict in Yemen is equally ephemeral.
One gets a vivid sense of America’s altered circumstances by comparing the U.S. response to the Arab Spring to its actions in the early years of the Cold War. In 1948, the Marshall Plan allocated roughly $13 billion in direct grants to restarting Europe’s economy, an amount equal to approximately 5 percent of total U.S. GDP. The equivalent amount today would be some $700 billion, and there is no way that Washington could devote even a tenth of that amount to helping Egypt, Tunisia, Libya or others. Nor does one need to go all the way back to 1948. The United States forgave $7 billion of Egypt’s foreign debt after the 1991 Gulf War; in 2011, all it could offer Cairo’s new government was $1 billion worth of loan guarantees (not actual loans) and $1 billion in debt forgiveness.
America’s declining influence is also revealed by its repeated failure to resolve the Israeli-Palestinian dispute. It has been nearly twenty years since the signing of the Oslo accords in September 1993, and the United States has had a monopoly on the “peace process” ever since that hopeful day. Yet its efforts have been a complete failure, proving beyond doubt that Washington is incapable of acting as an effective and evenhanded mediator. Obama’s call for “two states for two peoples” in his address to the Arab world in June 2009 produced a brief moment of renewed hope, but his steady retreat in the face of Israeli intransigence and domestic political pressure drove U.S. credibility to new lows.
Taken together, these events herald a sharp decline in America’s ability to shape the global order. And the recent series of economic setbacks will place even more significant limits on America’s ability to maintain an ambitious international role. The Bush administration inherited a rare budget surplus in 2001 but proceeded to cut federal taxes significantly and fight two costly wars. The predictable result was a soaring budget deficit and a rapid increase in federal debt, problems compounded by the financial crisis of 2007–09. The latter disaster required a massive federal bailout of the financial industry and a major stimulus package, leading to a short-term budget shortfall in 2009 of some $1.6 trillion (roughly 13 percent of GDP). The United States has been in the economic doldrums ever since, and there is scant hope of a rapid return to vigorous growth. These factors help explain Standard & Poor’s U.S. government credit-rating downgrade in August amid new fears of a “double-dip” recession.
The Congressional Budget Office projects persistent U.S. budget deficits for the next twenty-five years—even under its optimistic “baseline” scenario—and it warns of plausible alternatives in which total federal debt would exceed 100 percent of GDP by 2023 and 190 percent of GDP by 2035. State and local governments are hurting too, which means less money for roads, bridges, schools, law enforcement and the other collective goods that help maintain a healthy society.
The financial meltdown also undermined an important element of America’s “soft power,” namely, its reputation for competence and probity in economic policy. In the 1990s, a seemingly robust economy gave U.S. officials bragging rights and made the “Washington Consensus” on economic policy seem like the only game in town. Thomas Friedman (and other popular writers) argued that the rest of the world needed to adopt U.S.-style “DOScapital 6.0” or fall by the wayside. Yet it is now clear that the U.S. financial system was itself deeply corrupt and that much of its economic growth was an illusory bubble. Other states have reason to disregard Washington’s advice and to pursue economic strategies of their own making. The days when America could drive the international economic agenda are over, which helps explain why it has been seventeen years since the Uruguay Round, the last successful multilateral trade negotiation.
The bottom line is clear and unavoidable: the United States simply won’t have the resources to devote to international affairs that it had in the past. When the president of the staunchly internationalist Council on Foreign Relations is penning articles decrying “American Profligacy” and calling for retrenchment, you know that America’s global role is in flux. Nor can the United States expect its traditional allies to pick up the slack voluntarily, given that economic conditions are even worse in Europe and Japan.
The era when the United States could create and lead a political, economic and security order in virtually every part of the world is coming to an end. Which raises the obvious question: What should we do about it?
THE TWILIGHT of the American Era arrived sooner than it should have because U.S. leaders made a number of costly mistakes. But past errors need not lead to a further erosion of America’s position if we learn the right lessons and make timely adjustments.
Above all, Washington needs to set clear priorities and to adopt a hardheaded and unsentimental approach to preserving our most important interests. When U.S. primacy was at its peak, American leaders could indulge altruistic whims. They didn’t have to think clearly about strategy because there was an enormous margin for error; things were likely to work out even if Washington made lots of mistakes. But when budgets are tight, problems have multiplied and other powers are less deferential, it’s important to invest U.S. power wisely. As former secretary of defense Robert Gates put it: “We need to be honest with the president, with the Congress, with the American people . . . a smaller military, no matter how superb, will be able to go fewer places and be able to do fewer things.” The chief lesson, he emphasized, was the need for “conscious choices” about our missions and means. Instead of trying to be the “indispensable nation” nearly everywhere, the United States will need to figure out how to be the decisive power in the places that matter.
For starters, we should remember what the U.S. military is good for and what it is good at doing. American forces are very good at preventing major conventional aggression, or reversing it when it happens. We successfully deterred Soviet ambitions throughout the long Cold War, and we easily reversed Iraq’s invasion of Kuwait in 1991. The U.S. naval and air presence in Asia still has similar stabilizing effects, and the value of this pacifying role should not be underestimated.
By contrast, the U.S. military is not good at running other countries, particularly in cultures that are radically different from our own, where history has left them acutely hostile to foreign interference, and when there are deep ethnic divisions and few democratic traditions. The United States can still topple minor-league dictators, but it has no great aptitude for creating stable and effective political orders afterward.
It follows that the United States should eschew its present fascination with nation building and counterinsurgency and return to a grand strategy that some (myself included) have labeled offshore balancing.2 Offshore balancing seeks to maintain benevolent hegemony in the Western Hemisphere and to maintain a balance of power among the strong states of Eurasia and of the oil-rich Persian Gulf. At present, these are the only areas that are worth sending U.S. soldiers to fight and die in.
Instead of seeking to dominate these regions directly, however, our first recourse should be to have local allies uphold the balance of power, out of their own self-interest. Rather than letting them free ride on us, we should free ride on them as much as we can, intervening with ground and air forces only when a single power threatens to dominate some critical region. For an offshore balancer, the greatest success lies in getting somebody else to handle some pesky problem, not in eagerly shouldering that burden oneself.
To be more specific: offshore balancing would call for removing virtually all U.S. troops from Europe, while remaining formally committed to NATO. Europe is wealthy, secure, democratic and peaceful, and it faces no security problems that it cannot handle on its own. (The combined defense spending of NATO’s European members is roughly five times greater than Russia’s, which is the only conceivable conventional military threat the Continent might face.) Forcing NATO’s European members to take the lead in the recent Libyan war was a good first step, because the United States will never get its continental allies to bear more of the burden if it insists on doing most of the work itself. Indeed, by playing hard to get on occasion, Washington would encourage others to do more to win our support, instead of resenting or rebelling against the self-appointed “indispensable nation.”
In the decades ahead, the United States should shift its main strategic attention to Asia, both because its economic importance is rising rapidly and because China is the only potential peer competitor that we face. The bad news is that China could become a more formidable rival than the Soviet Union ever was: its economy is likely to be larger than ours (a situation the United States has not faced since the nineteenth century); and, unlike the old, largely autarkic Soviet Union, modern China depends on overseas trade and resources and will be more inclined to project power abroad.
The good news is that China’s rising status is already ringing alarm bells in Asia. The more Beijing throws its weight around, the more other Asian states will be looking to us for help. Given the distances involved and the familiar dilemmas of collective action, however, leading a balancing coalition in Asia will be far more difficult than it was in Cold War Europe. U.S. officials will have to walk a fine line between doing too much (which would allow allies to free ride) and doing too little (which might lead some states to hedge toward China). To succeed, Washington will have to keep air and naval forces deployed in the region, pay close attention to the evolving military and political environment there, and devote more time and effort to managing a large and potentially fractious coalition of Asian partners.
Perhaps most importantly, offshore balancing prescribes a very different approach to the greater Middle East. And prior to 1991, in fact, that’s exactly what we did. The United States had a strategic interest in the oil there and a moral commitment to defending Israel, but until 1968 it mostly passed the buck to London. After Britain withdrew, Washington relied on regional allies such as Iran, Saudi Arabia and Israel to counter Soviet clients like Egypt and Syria. When the shah fell, the United States created the Rapid Deployment Joint Task Force (RDJTF) but did not deploy it to the region; instead, it kept the RDJTF over the horizon until it was needed. Washington backed Iraq against Iran during the 1980s, and the U.S. Navy escorted oil tankers during the Iran-Iraq War, but it deployed U.S. ground and air forces only when the balance of power broke down completely, as it did when Iraq seized Kuwait. This strategy was not perfect, perhaps, but it preserved key U.S. interests at minimal cost for over four decades.
Unfortunately, the United States abandoned offshore balancing after 1991. It first tried “dual containment,” in effect confronting two states—Iran and Iraq—that also hated each other, instead of using each to check the other as it had in the past. This strategy—undertaken, as the National Iranian American Council’s Trita Parsi and Brookings’ Kenneth Pollack suggest, in good part to reassure Israel—forced the United States to keep thousands of troops in Saudi Arabia, sparking Osama bin Laden’s ire and helping fuel the rise of al-Qaeda. The Bush administration compounded this error after 9/11 by adopting the even more foolish strategy of “regional transformation.” Together with the “special relationship” with Israel, these ill-conceived approaches deepened anti-Americanism in the Middle East and gave states like Iran more reason to consider acquiring a nuclear deterrent. It is no great mystery why Obama’s eloquent speeches did nothing to restore America’s image in the region; people there want new U.S. policies, not just more empty rhetoric.
One can only imagine how much policy makers in Beijing have enjoyed watching the United States bog itself down in these costly quagmires. Fortunately, there is an obvious solution: return to offshore balancing. The United States should get out of Iraq and Afghanistan as quickly as possible, treat Israel like a normal country instead of backing it unconditionally, and rely on local Middle Eastern, European and Asian allies to maintain the peace—with our help when necessary.
DON’T GET me wrong. The United States is not finished as a major power. Nor is it destined to become just one of several equals in a future multipolar world. To the contrary, the United States still has the world’s strongest military, and the U.S. economy remains diverse and technologically advanced. China’s economy may soon be larger in absolute terms, but its per capita income will be far smaller, which means its government will have less surplus to devote to expanding its reach (including of the military variety). American expenditures on higher education and industrial research and development still dwarf those of other countries, the dollar remains the world’s reserve currency and many states continue to clamor for U.S. protection.
Furthermore, long-term projections of U.S. latent power are reassuring. Populations in Russia, Japan and most European countries are declining and aging, which will limit their economic potential in the decades ahead. China’s median age is also rising rapidly (an unintended consequence of the one-child policy), and this will be a powerful drag on its economic vitality. By contrast, U.S. population growth is high compared with the rest of the developed world, and U.S. median age will be lower than any of the other serious players.
Indeed, in some ways America’s strategic position is actually more favorable than it used to be, which is why its bloated military budget is something of a mystery. In 1986, for example, the United States and its allies controlled about 49 percent of global military expenditures while our various adversaries combined for some 42 percent. Today, the United States and its allies are responsible for nearly 70 percent of military spending; all our adversaries put together total less than 15 percent. Barring additional self-inflicted wounds, the United States is not going to fall from the ranks of the great powers at any point in the next few decades. Whether the future world is unipolar, bipolar or multipolar, Washington is going to be one of those poles—and almost certainly the strongest of them.
And so, the biggest challenge the United States faces today is not a looming great-power rival; it is the triple whammy of accumulated debt, eroding infrastructure and a sluggish economy. The only way to have the world’s most capable military forces both now and into the future is to have the world’s most advanced economy, and that means having better schools, the best universities, a scientific establishment that is second to none, and a national infrastructure that enhances productivity and dazzles those who visit from abroad. These things all cost money, of course, but they would do far more to safeguard our long-term security than spending a lot of blood and treasure determining who should run Afghanistan, Kosovo, South Sudan, Libya, Yemen or any number of other strategic backwaters.
The twilight of the American Era is not an occasion to mourn or a time to cast blame. The period when the United States could manage the politics, economics and security arrangements for nearly the entire globe was never destined to endure forever, and its passing need not herald a new age of rising threats and economic hardship ifwe make intelligent adjustments.
Instead of looking backward with nostalgia, Americans should see the end of the American Era as an opportunity to rebalance our international burdens and focus on our domestic imperatives. Instead of building new Bagrams in faraway places of little consequence, it is time to devote more attention to that “shining city on a hill” of which our leaders often speak, but which still remains to be built.
Stephen M. Walt is the Robert and Renee Belfer Professor of International Affairs at Harvard University’s Kennedy School of Government.
1 See Richard Rosecrance, ed., America as an Ordinary Country: U.S. Foreign Policy and the Future (Ithaca, NY: Cornell University Press, 1976); and Robert O. Keohane, After Hegemony: Cooperation and Discord in the World Political Economy (Princeton, NJ: Princeton University Press, 1984).
2 On “offshore balancing,” see Christopher Layne, “From Preponderance to Offshore Balancing: America’s Future Grand Strategy,” International Security 22, no. 1 (1997); John J. Mearsheimer, The Tragedy of Great Power Politics (New York: W. W. Norton, 2001); and Stephen M. Walt, Taming American Power: The Global Response to U.S. Primacy (New York: W. W. Norton, 2005), chap. 5.
斯蒂芬·沃尔特：美国时代的终结（The End of the American Era）
美国自1945年以来一直是占据主导地位的世界大国，而且美国领导人长期以来都在力求维持这种特权地位。像大多数的美国人一样，他们明白主导地位带来了重大的好处，使得其他国家不太可能直接威胁到美国或美国的切身利益。通过抑制大国竞争并使华盛顿拥有影响地区力量平衡的能力，主导地位促成一个更加安宁的国际环境。这种安宁促进了全球繁荣；一旦战争的危险减少，投资者和交易商带着更大的信心展开业务。主导地位还赋予了美国为积极目的——推进人权和防止大规模杀伤性武器的扩散——而工作的能力。虽然也许高处不胜寒，但美国人已发现这种看法是颇具说服力的。
然而，当一国独自处在权力巅峰之时，除了往下之外无处可去。因此美国人一再担心衰落的可能性——即便当这种可能性很是遥远的时候。早在1950年，国家安全委员会第68号文件就警告说，原苏联获得原子武器预示着地缘政治开始朝着有利于莫斯科的方向发生不可逆的转变。几年之后，原苏联人造卫星的发射导致许多人担心原苏联领导人尼基塔. 赫鲁晓夫 (Nikita S. Khrushchev)“埋葬”西方资本主义的誓言也许就要成真了。据报道，约翰.肯尼迪(John F. Kennedy)总统相信原苏联最终会比美国富有，而理查德.尼克松(Richard Nixon)则哀叹美国正在变成一个“可怜无助的巨人”。在之后10年左右的时间里，在印度支那的失败和反复出现的经济问题驱使著名学者撰写出了《美国：一个普通国家》(America as an Ordinary Country)和《霸权之后》(After Hegemony)这样的作品。有关原苏联主导地位过于牵强的担忧将罗纳德.里根(Ronald Reagan)推上了总统的宝座，而且被用来证明20世纪80年代初的大规模扩军是正当的。现在看来，自美国登上全球力量的顶峰以来，衰落迫在眉睫的担心就一直与美国同在了。
随着保罗.肯尼迪(Paul Kennedy)的畅销书《大国的兴衰》(Rise and Fall of the Great Powers)的出版，有关衰落的各种论述具有了新的生命，该书坚持认为，美国处于“帝国过度扩张”的危险之中，肯尼迪相信，英国之所以回到不体面的平庸之国行列，是因为它花了太多的钱去捍卫广泛的利益和投身代价高昂的战争，而且他警告说，美国将被牵着走上一条类似的道路。约瑟夫.奈(Joseph Nye)在《美国注定领导世界：美国权力性质的变迁》(Bound to Lead：The Changing Nature of American Power)一书中对肯尼迪的悲观主义提出了挑战，虽然该书销量不大，但却提供了一个更加准确的近期预测。约瑟夫.奈强调美国具有不同寻常的优势，坚持认为它在今后许多年里注定成为最重要的世界大国。
从那时以来，一大批书籍和文章——从查尔斯.克劳萨默(Charles Krauthammer)的《单极时刻》(The Unipolar Moment)、约翰.伊肯伯里(G. John Ikenberry)的《自由利维坦》(Liberal Leviathan)和尼尔.弗格森(Niall Ferguson)的《巨人:美帝国的崛起和衰落》(Colossus:the Rise and fall of the American Empir)到法里德.扎卡里亚(Fareed Zakaria)的《后美国世界》(The Post-American World)等等——已就美国优势可能延续多久展开了辩论。甚至连本.拉登(Osamabin Laden)最终也插足其中，宣称在伊拉克和阿富汗的战争是对美国力量的致命打击，并为基地组织的恐怖活动平了反。
然而，被泼在美国主导地位耐久性上的所有墨水，主角们多半弄错了问题。问题从来就不是美国是否将要追随英国跌出大国行列，或者遭受某种其他形式的灾难性衰落。真正的问题始终是所谓的“美国时代”是否正在接近终点。也即美国可能依旧是最强大的全球性大国，但却无法行使它曾经享有的同样影响力吗？如果是这样的话——而且我相信是这样的——那么华盛顿就必须制定一项大战略来承认这种新现实并继续利用美国的长期资产来推进国家利益。
美国时代是紧接着二次大战的结束而开始的。欧洲虽然在三个多世纪里也许一直是国际政治的中心，但两次毁灭性的世界大战毁灭了这些大国中的大部分。国务院政策计划室在1947年宣布，“超强大国必然成为美国政策的目标”，而公开承认这一目标的意愿足以说明力量的不平衡是有利于美国的。虽然国际关系学者常说这一时刻是从一个多极世界向两极世界的一个过渡，但冷战的两极性从一开始就是明确地倾向于一方的。
例如在1945年，美国的经济产出占到世界产出总量的将近一半，而且美国是一个有着积极贸易平衡的主要债权国。它拥有世界上最大规模的海军和空军、首屈一指的工业基础，是唯一拥有原子武器以及军事基地遍布全球的国家。通过支持非殖民化以及通过马歇尔计划支持欧洲重建，美国在发达和发展中世界的大多数地区也获得了相当大的敬意。
最重要的是，美国处于一个极为有利的地缘政治位置上。在西半球没有任何其他大国，美国人不必担心外敌的入侵。原苏联的经济体量小得多，效率也低。其军事实力主要集中在地面部队上，从未逼近美国力量所及的全球范围。其他主要权力中心全都位于或者接近于欧亚大陆——靠近原苏联而远离美国——这使得甚至诸如德国和日本那样的前对手也急于寻求美国的保护，以免受到“俄罗斯熊”的威胁。因此，随着冷战继续进行，美国汇聚了一批强大和忠诚的盟国，而原苏联则领导着一个由软弱和勉强的合作伙伴组成的联盟。总之，即便在原苏联解体之前，美国的整体地位跟现代历史上任何大国的总体地位一样，基本上是有利的。
美国利用这些令人印象深刻的有利条件做了些什么呢？在二次大战后的几十年里，它在全球各地创建和左右了一个政治的、安全和经济的秩序，除了原苏联及其共产党代理人直接控制的范围。美国不仅将世界的大部分地区带入了主要是美国所创建的机构(联合国、世界银行、国际货币基金组织、关贸总协定)，而且几十年来，它在这些安排上保持着主导影响力。
在欧洲，马歇尔计划振兴了当地经济，美国暗中干预帮助并确保各共产党无法掌权，而北约组织则确保了和平并抵御原苏联的军事压力。盟军最高司令的职位始终为美国官员所保留，而且没有美国的支持和同意就不会有任何意义重大的欧洲安全倡议；通过与日本、韩国、澳大利亚、新西兰、菲律宾和其他几个国家(和地区)签订双边条约，美国在亚洲建立了一个同样持久的安全秩序，而且将这些国家都纳入一个日趋自由的世界经济里；在中东地区，华盛顿不久帮助建立和保卫以色列，而且还与沙特、约旦、伊朗和几个较小海湾国家建立了密切的安全关系；美国在西半球继续行使霸权地位，运用各种手段驱逐危地马拉、多米尼加、智利和尼加拉瓜的左翼政府；在非洲，由于未将非洲看成是一个至关重要的竞技场，美国的所作所为刚好足够确保其在那里不太多的利益。
可以肯定的是，美国对所创建的各种地区性秩序中所发生的各种事件并未施加全面控制。它无法阻止1959年的古巴革命或1979年的伊朗革命，它在1966年未能阻止法国退出北约组织的军事一体化指挥机构，而且它也未能阻止以色列、印度、朝鲜和巴基斯坦获得核武器。但是，美国在这些地区里的每个问题尤其重大问题上保持着巨大的影响力。
此外，虽然美国的地位有时遭到了挑战——在越南遭受的失败便是最为明显的例子——但美国的总体地位从未处于危险之中。尽管在亚洲失败了，但美国与亚洲的联盟体系却依旧是紧密联系的，而在20世纪70年代期间，北京与华盛顿形成了一种心照不宣的伙伴关系。同样，虽然一旦神职政权接管，伊朗就变成为一个对手，但美国在中东地区的整体地位并未动摇。石油继续从波斯湾地区流出，以色列变得越来越安全和繁荣，而且像埃及这样的原苏联核心盟国最终抛弃了莫斯科，并站到了美国一边。尽管偶尔受挫，但美国时代的本质特征依旧十分牢固。
不用说，对于一个只占世界人口5%的国家来说，有能力在全球各地构建起有利的政治、经济和安全秩序并将其维持长达数十年，这是极不寻常的。然而，这就是美国从1945-1990年所做的事，而且在这么做的同时还享受着长达半世纪、在现代历史上几乎无可匹敌的经济增长。
随后，原苏联帝国崩溃，使得美国成为一个单极世界里唯一的超级大国。据前国家安全顾问布伦特.斯考克罗夫特(Brent Scowcroft)所说，美国发现自身“孤独地处于权力的巅峰。这在过去和现在都是历史上前所未有的，为我们提供了影响世界的最难得机会”。因此它尝试将华约组织大多数成员带入北约组织，并鼓励市场经济和民主体制扩展到整个前共产主义世界。这是一个凯旋的时刻——美国时代的巅峰——但这些庆祝的焰火却使我们看不见促使这个时代结束的各种趋势和陷阱。
过去20年已经目睹了新权力中心在几个关键地区的形成。最明显的例子便是中国，其爆炸性的经济增长无疑是几十年来意义最重大的地缘政治发展。虽然美国自大约1900年以来一直是世界上最大的经济体，但中国可能最晚于2025年在经济总量上赶上美国。如果中国像所有从前的大国——包括美国一样，那么其对“切身”利益的定义将会随着权力增强而拓展——而且将会设法利用日益增长的力量来保护一个不断扩大的势力范围。鉴于对原材料进口(特别是能源)和出口导向型增长的依赖，深谋远虑的中国领导人将希望确保无人能够拒绝给予他们获得未来的繁荣和政治稳定所需的各种资源和市场的机会。
这种情况将会鼓励北京挑战目前美国在亚洲所扮演的角色。鉴于美国自门罗主义以来一直力求将外来大国排除在其临近地区之外，让美国人理解这类雄心不应很困难。依照类似的逻辑，如果华盛顿在东亚和印度洋保持一个亚洲联盟和一个庞大的军事存在的话，那么中国必然会感到不安。随着时间的推移，北京将设法说服亚洲其他国家放弃与美国之间的关系，而且华盛顿将几乎肯定会抵制这些努力，随之而来的便将是一场激烈的安全竞争。
界定美国时代的各种安全安排因几个关键性地区大国(最主要的是印度、土耳其和巴西)的崛起而正在被削弱。这些国家在过去10年中都已取得了令人惊讶的经济增长，而且都变得更不愿受华盛顿愿望的支配，都在勾画各自要走的路。它们没有变成真正的全球性大国——巴西的GDP仍然不到美国的1/6，而印度和土耳其的经济规模甚至更小——但它们在各自地区范围内已变得越来越具有影响力。从八国集团最近扩展成所谓的二十国集团中也可以看到权力的这种逐步扩散，这是一种默认，即二战后建立的这一全球性机构已显得过时并需要改革。
这些新的地区性大国都是民主国家，这意味着其领导人密切关注舆论。因此，美国不可能再依靠与特权精英或军政府所形成的舒适关系。当仅有10%～15%的土耳其居民对美国抱有一种“有利的”看法时，那就不难理解为何安卡拉在2003年拒绝让华盛顿利用其领土攻击伊拉克，以及为何尽管美国为弥合裂痕而做出了多次努力，但土耳其却疏远了先前与以色列之间的密切关系。虽然反美主义在巴西和印度并不太普遍，但它们的民选领导人对华盛顿并不恭顺。
新的大国的崛起将导致短命的“单极时刻”的结束，而且结果或者是一个两极体系的中美竞争，或者是一个包含几个地位不等的大国的多极体系。虽然美国可能依然是最强大的，但总体领先地位已缩小了——而且正在进一步缩小。
当然，在伊拉克和阿富汗的孪生灾难只会加速美国优势的减弱，并凸显美国力量的各种局限。一旦所有成本都被算上，光是伊拉克战争就将意味着价码超过3万亿美元，而最终的结果可能是一个公开敌视以色列和至少部分与伊朗结盟的不稳定的准民主国家。事实上，伊朗一直是这种拙劣冒险的主要受益者，它将伊拉克拖入了战争，而这肯定不是布什政府想要的东西。
即使美国领导人最终设法将这杜撰为某种胜利，但漫长的阿富汗军事行动的结局甚至更有可能得不到体面的收场。虽然奥巴马政府最终杀了拉登，但为消灭塔利班并在阿富汗建立一个西方式国家所做出的漫长而代价昂贵的努力已经宣告失败。此时此刻，唯一令人感兴趣的问题便是美国的撤出是快还是慢。无论如何，一旦美国以及盟国撤离，喀布尔的命运终将由阿富汗人来决定。
如果在阿富汗的失败还不足够的话，那么美国介入中亚地区则已损害了美国与拥有核武器的巴基斯坦之间的关系，并加剧了这个困境国家中充满仇恨的反美主义。如果胜利被界定为实现主要目标并结束一场战争，安全和繁荣程度获得增强，那么这些冲突肯定只能算是代价昂贵的失败。
但是，伊拉克和阿富汗的战争不只是代价昂贵的自伤行为；它们也充分展示了军事力量的各种局限性。美国能够推翻相对衰弱和/或不受欢迎的政府——正如它在巴拿马、阿富汗、伊拉克和利比亚所做的——人们对此从来不曾有多少怀疑，但在伊拉克和阿富汗的战争却表明，一旦令人厌恶的领导层被赶下台，无可匹敌的力量投放在构建有效的政治秩序上几乎毫无用处。在那些地方特征依旧非常浓厚以及外来干预长期以来一直不受欢迎的地方，即便像美国这样一个全球超级大国在获得理想政治结果方面也遇到了麻烦。
这一点在大中东地区表现得最为明显，该地区自原苏联解体以来一直是美国战略的主要焦点。阿拉伯之春不仅使华盛顿感到意外，而且美国的反应进一步暴露出让事件有利于自身的能力减弱了。在短暂地极力支撑穆巴拉克政权之后，奥巴马政府重新调整了自身与挑战现有地区性秩序的各种力量之间的关系。虽然奥巴马总统举行了一场雄辩的演说赞同变革，但该地区无人给予多少重视。事实上，除了利比亚这个例外，美国对整个过程的影响力始终是不太大的。奥巴马无力阻止沙特向巴林派兵——利雅得在那里帮助平息了要求改革的呼声——或者说服叙利亚领导人巴沙尔.阿萨德(Bashar al-Assad)下台。美国在埃及后穆巴拉克政治过程以及在也门一触即发的冲突中的影响力同样也是短暂的。
通过比较美国对阿拉伯动乱的反应及其在冷战初期的行动，人们便会对美国境况的改变产生一种强烈感受。1948年，“马歇尔计划”直接拨款约130亿美元以重启欧洲经济，这一数量大约相当于美国当时GDP的5%。今天这一比例相当于约7000亿美元，而华盛顿根本不可能把这一数额的1/10用于帮助埃及、突尼斯、利比亚或其他国家。人们也不必大老远地回到1948年。美国在1991年海湾战争后减免了埃及70亿美元外债；而在2011年，它所能提供给开罗新政府的一切，只是价值10亿美元的贷款担保(而不是实际的贷款)以及10亿美元债务减免。
美国不断下降的影响力也因其无力解决以巴争端而暴露无遗。自1993年9月签署《奥斯陆协议》以来已有近20年了，而且美国那时对“和平进程”还拥有一种垄断地位。但美国所做出的努力始终是失败的，从而毫无疑问地证明华盛顿无力充当一个有效而不偏不倚的调停者。奥巴马在2009年6月对阿拉伯世界发表的演说中发出“两国人民两个国家”的呼吁虽然瞬间重燃了希望，但面对以色列的顽固立场以及国内政治压力，奥巴马步步退却，将美国的信誉推入新低点。
这些事件预示着美国影响全球秩序的能力在急剧下降。而最近的一系列经济挫折则进一步限制了美国保持一个雄心勃勃的国际角色的能力。虽然布什政府在2001年继承了一个罕见的预算盈余，但它继续大幅度削减联邦税，而且打了两场代价昂贵的战争。可想而知，结果便是预算赤字暴增和联邦债务骤增，而各种问题因2007-2009年的金融危机而加剧了。后一场灾难需要联邦大规模救助金融业和一项巨额的经济刺激计划，从而在2009年导致了约1.6万亿美元(约占GDP的13%)的短期预算赤字。美国自那时以来一直处在经济低迷之中，几乎失去了迅速恢复强劲增长的希望。这些因素有助于解释标准普尔公司在新的“两次探底”衰退的恐惧中于2011年8月调低了美国政府的信用评级。
国会预算办公室预测，即使在乐观的基线情景之下，美国在未来25年里将继续面对预算赤字——而且它警告说，在看似合理的可选择情景里，联邦债务总额到2023年时将超过GDP的100%，而到2035年时将占到GDP的190%。各州和地方政府也将受到伤害，意味着用于道路、桥梁、学校、执法和帮助保持一个健康社会的其他公共产品的资金减少了。
金融风暴也削弱了美国“软实力”中的一个主要要素，即经济政策的能力和正直诚实的声誉。20世纪90年代，看似强大的经济体给了美国官员吹牛的权利，并使得经济政策上的“华盛顿共识”看起来像是唯一之选。托马斯.弗里德曼(Thomas Friedman)等坚持认为，世界其他地区有必要采取美式的“ DOScapital 6.0”，否则将会半途而废。然而，现在有一点是清楚的，美国的金融体系极其腐败，而且经济增长的大部分是一个虚幻的泡沫。其他国家有理由不接纳华盛顿的劝告并推行各自的经济战略。美国能够推动国际经济议程的日子已经结束了，这有助于解释为何自乌拉圭回合(最近一次成功的多边贸易谈判)以来时间已过去了17个年头。
底线是很明确的和不可避免的：美国根本不再拥有它过去所拥有的用于国际事务的资源。当身为坚定国际主义者的对外关系理事会主席理查德.哈斯(Richard Haass)撰文谴责“美国的肆意挥霍”并呼吁收缩之时，你就会明白美国的全球性角色是在不断变动中的。鉴于欧洲和日本的经济状况更加糟糕，美国也不可能指望传统盟国自愿来收拾烂摊子。
美国能够在世界各地创建并主导一种政治、经济和安全秩序的时代即将结束。这就产生了一个显而易见的问题：美国对此该做些什么呢？
美国时代的衰亡之所以加速提早到来，是因为美国的领导人犯下了许多代价昂贵的错误。但如果美国汲取正确的教训并做出及时的调整，那么过去的错误未必会导致美国的地位的进一步削弱。
最重要的是，华盛顿需要设定明确的优先事项，并需要采取脚踏实地和头脑冷静的做法来保护美国最重要的利益。当美国的主导地位处在巅峰之时，美国的领导人对利他主义的怪念头是有求必应。他们不必清楚地思考战略，因为存在一个巨大的失误空间；即便华盛顿犯下很多错误，事情也能顺利获得解决。但当预算紧张时，问题成倍地增加了，而且其他大国又变得不那么恭敬，明智地投资美国的力量是很重要的。正如国防部前部长罗伯特.盖茨(Robert Gates)所说：“我们要对总统、国会、国人说实话……一支规模较小的军队，无论能力多么高超，能够去的地方将更少，能够做的事将更少。”他强调说，主要的教训是需要对有关的使命以及手段做出“有意识的选择”。不是设法在任何地方都成为“不可或缺的国家”，美国将需要弄清楚在重要的地方如何成为决定性大国。
首先，我们应该记住美军对什么是有好处的以及它擅长于做什么。美军极擅长于防止重大的常规性入侵，或者当入侵发生时彻底将其扭转。在整个漫长的冷战时期，美国成功地抑止了原苏联的野心，而且毫不费力地彻底扭转了1991年伊拉克对科威特的入侵。美国海空军在亚洲的存在仍然有着类似的稳定效果，而且这种安抚角色的价值不应被低估。
相比之下，美军不擅长于管理其他国家，特别是在完全不同的文化里以及当存在根深蒂固的种族分歧和几乎没有民主传统的时候。在那里，历史已经使得它们对外来干涉抱有深深的敌意。虽然美国仍能推翻较小联盟的独裁者，但对此后创建稳定和有效的政治秩序并无任何卓越才能。
由此可见，美国应该抛开目前对国家建设和平叛的迷恋，回到有些人(包括我)所说的离岸平衡标签的一项大战略。离岸平衡战略力求维持西半球的仁慈霸权，并力求保持欧亚大陆以及盛产石油的波斯湾之间强国的力量平衡。目前，只有这些地区才是值得美军士兵去打仗和送死的。
然而，不应寻求直接地去主宰这些地区，美国的第一个依靠应该是让当地的盟国出于它们自身利益去支撑力量平衡。不是让它们免费搭美国的便车，美国应该尽可能多地免费搭它们的便车，只有当某个大国有主宰某个关键地区的危险时，才动用地面和空中力量进行干预。对于离岸平衡而言，最大的成功在于让别人来处理一些令人讨厌的问题，而不是急切地自己去扛那份重担。
更具体地说：离岸平衡战略将要求从欧洲撤出几乎所有的美军，同时正式向北约做出承诺。欧洲是富有的、安全的、民主的和安宁的，而且它并未面临任何它无力自行处理的安全问题。北约欧洲成员国的国防开支总额比俄罗斯大5倍左右，后者是欧洲大陆可能面对的唯一可以想象得到的常规军事威胁。迫使北约的欧洲成员主导最近的利比亚战争，这是一个良好的开端，因为如果它坚持自己来做该项工作的大部分，那美国也永远不会让欧洲大陆的盟国承受更大负担的。事实上，华盛顿有时采用欲擒故纵的做法，鼓励别国出更多的力，而不是怨恨或反抗这个自命的“不可或缺的国家”，以便赢得美国的支持。
在未来几十年里，美国应该将主要战略关注点转向亚洲，因为亚洲经济上的重要性正在迅速提升，也因为中国是美国所面对的唯一潜在的、地位对等的竞争对手。坏消息是中国可能变成一个比原苏联更强的竞争对手：其经济规模可能会超过美国(这是美国自19世纪以来从未曾面对的情况)，而且，不像主要是自给自足的原苏联，现代中国依赖海外贸易和资源，而且将会更倾向于向国外投放力量。
好消息是中国不断上升的地位已经在亚洲引起关注。北京的实力越强，其他亚洲国家就越指望我们提供帮助。可是，鉴于集体行动所涉及的距离以及令人熟悉的困境，在亚洲领导一个平衡联盟比在冷战时期的欧洲将会困难得多。美国官员将不得不在做得太多(这将允许盟友免费搭车)以及做得太少(这可能导致一些国家围堵中国)之间小心行事。为了取得成功，华盛顿将不得不继续在该地区部署海空军，密切关注那里不断变化的军事和政治环境，并投入更多的时间和精力来管理一个由亚洲合作伙伴组成的庞大联盟。
也许最重要的是，离岸平衡战略为如何应对大中东地区规定了一种极为不同的做法。而在1991年以前，这其实正是美国所做的事。虽然美国在那里的石油上有着战略利益，而且对捍卫以色列存有道义上的承诺，但到了1968年，它把责任大多推给了伦敦。在英国撤出之后，华盛顿依赖诸如伊朗、沙特和以色列这类地区性盟国来对付诸如埃及和叙利亚这样的原苏联代理人。当伊朗国王下台时，虽然美国组建了快速部署联合特遣部队(RDJTF)，但并未将其部署到该地区；相反，它将快速部署联合特遣部队一直保持在地平线上，直到需要之时。华盛顿在20世纪80年代期间支持伊拉克对抗伊朗，而且美国海军在两伊战争期间护送油轮，但只有当力量平衡完全被打破时，它才会派遣地面部队和空中力量，正如它在伊拉克占领科威特时所做的。这项战略也许并不完美，但在长达40多年的时间里，它以最低的成本维持了美国的关键利益。
遗憾的是，美国在1991年之后放弃了离岸平衡战略。它首先尝试“双重遏制”战略，实际上对抗两个国家 ——伊朗和伊拉克，而且彼此憎恨，而不是像以往那样用一国来牵制另一国。采用这项战略，正如全美伊朗裔人理事会的特里达.帕西(Trita Parsi)和布鲁金斯学会的肯尼斯.波拉克(Kenneth Pollack)所暗示的，善意地让以色列感到放心——迫使美国在沙特部署派驻数千驻军，从而激起本.拉登的愤怒，并帮助推动了“基地”组织的崛起。“911”事件后，通过采取更加愚蠢的“地区转型”战略，布什政府错上加错，连同与以色列的“特殊关系”，这些拙劣的做法加剧了中东地区的反美主义，并使得伊朗这样的国家更有理由考虑获得核威慑力量。为何奥巴马的雄辩演说对于重塑美国在该地区形象没有什么用处，个中并无神秘之物；那里的人民希望美国推行新政策，而不只是空洞的辞令。
看着美国陷入这样的泥潭，足以想象北京的决策者从中享受到了多大的乐趣。幸运的是，有一项显而易见的解决方案：重拾离岸平衡战略。美国应该尽快从伊拉克和阿富汗脱身，把以色列看作一个正常国家，而不是无条件地支持它，并依靠中东当地国家以及欧洲和亚洲的盟友来维持和平——有必要时，我们就提供帮助。
请不要误会。美国作为一大强国还没有失败。它也不会注定成为未来多极化世界里几个地位对等的大国之一。相反，美国仍然拥有世界上最强大的军队，而且美国经济仍然是多样化的，技术是先进的。虽然中国的经济在绝对值方面可能很快就会变得更大，但其人均收入仍将小得多，这意味着该国政府用于扩展势力范围的盈余并不多。美国在高等教育和工业研发上的支出依然使得其他国家相形见绌，美元依旧是当今世界的储备货币，而且许多国家继续吵闹着要美国提供保护。
此外，对美国潜在力量的长期预测是令人安心的。俄罗斯、日本和欧洲大多数国家的人口正在继续减少和老龄化，这将会限制它们在未来几十年的经济潜力。中国的年龄中位数也在迅速提高，而这将成为其经济活力的一个强大阻力。相比之下，与发达世界的其他地区相比，美国人口增长是很快的，而且美国的年龄中位数将低于任何其他重要的行为体。
其实，美国的战略地位在某些方面变得比以往更加有利了，这是为何膨胀的军事预算有几分神秘的原因。例如，在1986年，美国及其盟国支配了全球军费开支的约49%，而美国的各种对手加在一起也只占到约 42%。今天，美国及其盟国占到军费开支将近70%，而所有对手加在一起的总额还不到15%。除非新增的自伤，否则美国在未来几十年里不会跌出大国之列。无论未来的世界是单极的、双极的还是多极的，华盛顿将成为这些极之一——而且几乎肯定是这些极当中最为强大的。
所以，美国今天所面临的最大挑战并不是一个隐现的大国对手，而是累积的债务、正在削弱的基础设施和不景气的经济这三重打击。无论现在乃至未来，拥有世界上最强大军事力量的唯一办法，便是拥有世界上最发达的经济体，而这意味着拥有更好的学校、最好的大学、首屈一指的科研机构以及一个有效并让国外访客感到眼花的全国性基础设施。当然，这些东西全都是要花钱的，但较之将许多生命和财产花费在决定由谁来掌管阿富汗、科索沃、利比亚、也门或者任何其他战略落后地方上，它们将远远更有助于保障美国的长期安全。
美国时代的黄昏，不是一个哀悼的场合或者一个嫁祸于人的时刻。美国能为整个全球提供政治、经济和安全安排的时期从来没有命中注定会永久持续下去，而一旦美国做出明智调整，那么这个时代的消逝未必预示着威胁的不断增加和经济困难新时代的来临。
不要带着怀旧感回头看，相反，美国人应该将美国时代的终结看作是一个重新平衡美国的国际负担并注重国内当务之急的机遇。不是在无足轻重的偏远地方建立新的巴格拉姆空军基地，现在该将更多的注意力投放在美国领导人虽然经常谈及、但依旧尚待建造的那座“山巅上的光辉之城”了。
