The conventional wisdom these days is that Americans are war-weary. But it may be more accurate to say they are world-weary. During the cold war, after all, Americans had much greater reason for war-weariness—Korea and Vietnam were 14 times more costly in terms of American deaths than Afghanistan and Iraq—but they never fully rejected the global anti- communist containment strategy that had gotten them into the wars. Today’s mood seems more analogous to the 1920s. More than 50 percent of Americans today believe that the United States “should mind its own business internationally and let other countries get along the best they can on their own”—the highest number ever recorded since Pew started asking the question 50 years ago.

At the core of this public attitude is no doubt the desire to avoid more wars. But as the 1920s and 1930s showed, a determination to stay out of war can affect broader foreign and economic policies. In the 1930s, the desire to avoid war led Congress to pass the Neutrality Acts, to prevent Americans from even trading with belligerents in a foreign war lest the United States be dragged in on one side or the other. Such an action may be inconceivable today, but the reasoning behind it is visible. Polls these days show that Americans are not only averse to using military force but also to actions short of war. More than 50 percent agreed that it was “more important” that the United States “not get too involved in the situation in Ukraine” than that it “take a firm stand” against Russia, which 29 percent found more important. Many of those not wanting to get “too involved” may fear that any involvement could eventually lead to a possible military confrontation—and they’re not entirely wrong. As in the 1920s and 1930s, Americans can see the slippery slope.

IV.

Historians often refer to the “maturing” of American foreign policy since the nineteenth century. But if nations can learn, they can also unlearn. These days it is hard to watch both the conduct and the discussion of American foreign policy and not sense a certain unlearning, a forgetting of the old lessons on which the grand strategy was premised. Perhaps this was inevitable. World War II is as distant from today’s “millennials” as the Civil War was from the generation of the 1930s. A generation that does not remember the cold war, but grew up knowing only Iraq and Afghanistan, is going to view America’s role in the world differently. Combine that with the older generations that have tired of playing the old role, and it is hardly surprising that enthusiasm is flagging. Americans today are not isolationists, any more than they were in the 1920s. They favor the liberal world order insofar as they can see how it touches them. But they are no longer prepared to sacrifice very much to uphold it.

This is understandable. Americans have been Atlas carrying the world on their shoulders. They can be forgiven for feeling the temptation to put it down. Under the best of circumstances, playing the role of upholder of the liberal world order was always a monumental task. At the dawn of the American era, Truman called it “the most terrible responsibility that any nation ever faced.” George Kennan was convinced that the American people were “not fitted, either institutionally or temperamentally, to be an imperial power in the grand manner.” Actually, he underestimated them, for Americans maintained their global commitments for decades, better than most nations.

Yet the burden has been immense, and not just the obvious costs in lives and treasure. Americans have spent vast amounts on defense budgets, more than all other major powers combined. Can’t U.S. allies carry more of the burden? The question has been asked since the dawn of the cold war, but the answer has always been: probably not. The same factors that have made the United States uniquely capable of supporting a world order—great wealth and power and the relative security afforded by geography—help explain why American allies have always been less capable and less willing. They have lacked the power and the security to see and act beyond their narrow interests. So where they failed before they will fail again. Even twenty-first-century Europeans, for all the wonders of their union, seem incapable of uniting against a predator in their midst, and are willing, as in the past, to have the weak devoured if necessary to save their own (financial) skins. There are moral costs, too. Like most people, Americans generally like to believe that they are behaving justly in the world, that they are on the side of the right. If possible, they like to have legal or institutional sanctions for their action, or at least the general approval of like-minded nations. On the two occasions in the past 100 years when the United States contemplated taking on a central role in global affairs, in 1918 and 1945, American leaders insisted on simultaneously creating world organizations that could, at least in theory, provide this legitimacy for American actions.

The problem is, the world lacks any genuine overarching legal or institutional authority, much less a democratic authority, to which all nations subordinate themselves. Questions of right and wrong are settled not according to impartial justice but usually according to the distribution of power in the system. Americans have usually had to use their power to enforce their idea of justice without any assurance beyond their own faith that they are right. This is a heavy moral burden for a democratic people to bear. In their domestic lives, Americans are accustomed to having that burden spread evenly across society. The people make the laws, the police enforce the laws, judges and juries mete out justice, and the prison officials carry out the punishment. But in the international sphere, Americans have had to act as judge, jury, police, and, in the case of military action, executioner. What gives the United States the right to act on behalf of a liberal world order? In truth, nothing does, nothing beyond the conviction that the liberal world order is the most just.

This moral conundrum was easier to ignore during the cold war, when every action taken, even in the most obscure corners of the world, was justified as being in defense of vital national interests. But actions taken in defense of world order are fraught with moral complexity. Americans and Europeans argue that Ukraine’s sovereignty should be inviolate and that the people of Ukraine should be allowed to pursue their aspirations to be part of Europe. Vladimir Putin justifies his invasion of Crimea on the grounds of ancient historical ties and in response to American and European meddling in Russia’s historical sphere of influence. Who is there to adjudicate between these competing claims of justice? Who can determine which side is right and which side is wrong? It does no good to invoke some allegedly superior twenty-first-century morality against an inferior nineteenth-century morality. No more in this century than in previous centuries is there either perfect morality or perfect justice to be found in the international system. Nor do great powers come to disputes with clean hands, in this or any other century. All are selfish; all are morally compromised. And indeed, the more power a nation has, the more it is likely to act in ways that cannot be squared with a Christian or Enlightenment morality.

Who is to say that even defense of the liberal world order is necessarily good? The liberal world order was never put to a popular vote. It was not bequeathed by God. It is not the endpoint of human progress, despite what our Enlightenment education tells us. It is a temporary and transient world order that suits the needs, interests, and above all the ideals of a large and powerful collection of people, but it does not necessarily fit the needs and desires of everyone. For decades many abroad and some Americans at home saw it as a form of Western imperialism, and many still do. Communism may have failed, but authoritarianism and autocracy live on. And it is that form of government, not democracy, that has been the norm throughout history. In recent decades the democracies, led by the United States and Europe, have had the power to shape the world. But who is to say that Putinism in Russia or the particular brand of authoritarianism practiced in China will not survive as far into the future as European democracy, which, outside of Great Britain, is itself only a little over a century old?

A liberal world order, like any world order, is something that is imposed, and as much as we in the West might wish it to be imposed by superior virtue, it is generally imposed by superior power. Putin seeks to impose his view of a world order, at least in Russia’s neighborhood, just as Europe and the United States do. Whether he succeeds or fails will probably not be determined merely by who is right and who is wrong. It will be determined by the exercise of power.

This is a disturbing thought for a nation that has grown weary of exercising power. Hans Morgenthau once observed that Americans are attracted to the “illusion that a nation can escape ... from power politics,” that at some point “the final curtain would fall and the game of power politics would no longer be played.” Many escapes have been offered over the past two decades. In 1989, Fukuyama told Americans that with the end of history there would be no more “serious ideological competitors left to liberal democracy.” Liberal progress was inevitable, and therefore nothing need be done to promote or defend it. Such thoughts were echoed throughout the 1990s. The age of geopolitics had supposedly given way to the age of geoeconomics. What America needed in the new era was less “hard power” and more “soft power.”

Such was the reigning conventional wisdom, at least from the end of the cold war until 2008 and the beginning of the financial crisis. Then the paradigm shifted. Suddenly, instead of the end of history, it was the end of America, the end of the West. Triumphalism turned to declinism. From the post-cold-war utopia it became the post-American world. Yet this, too, turned out to be a form of escapism, for remarkably, whether the liberal world order was triumphing or America and the West were declining, the prescription remained the same: There was nothing to be done. Whereas before it had been unnecessary, and even wrong, for the United States to use its power to shape the world, now, suddenly, it was impossible, because the United States no longer had sufficient power.

Today more than 50 percent of Americans believe the United States plays “a less important and powerful role as a world leader than it did a decade ago.” One senses that, for many Americans, this decline is not a reason for panic but comes as something of a relief. Less power means fewer responsibilities. A sense of futility, today as much as in the 1920s and 1930s, is both an invitation and a justification for a return to normalcy.

The sense of futility has affected policymakers, too. Senior White House officials, especially the younger ones, look at problems like the struggle in Syria and believe that there is little if anything the United States can do. This is the lesson of their generation, the lesson of Iraq and Afghanistan: that America has neither the power nor the understanding nor the skill to fix problems in the world.

This is also escapism, however, for there is a myth embedded in this plea of futility. It is that wielding power effectively was ever any easier than it is today. With rose-colored glasses we look back at the cold war and imagine that the United States used to get others to do what it wanted, used to know what it was doing, and used to wield such overwhelming power that the world simply bent to its will or succumbed to its charms. But American policy during the cold war, despite its ultimate success, was filled with errors, folly, many near-disasters, and some disasters. From the beginning, allies proved rebellious, resentful, and unmanageable. American domestic politics made sensible policies difficult and sometimes impossible to sustain. The world economy, and the American economy, lurched from crisis to crisis. American military power was at its best a most uncertain instrument. In Vietnam, whether inevitably or because of bad policymaking in Washington, it failed miserably. In Korea, it almost suffered a complete catastrophe. The most successful presidents of the era, from Truman to Reagan, did not always seem successful to their contemporaries and suffered significant setbacks in their foreign policies. Can the architects of today’s foreign policies really believe that Acheson and his colleagues, or the policymakers in the Johnson or Nixon or Carter administrations, had an easier time of it?

Any nation’s foreign policy is bound to fail more often than it succeeds. The attempt to influence the behavior of people even in the domestic setting is difficult enough. To influence other peoples and other nations without simply annihilating them is the most difficult of all human tasks. It is also in the very nature of foreign policy, as in human affairs generally, that all solutions to problems only breed more problems. This is certainly true of all wars. There is no perfect ending to any war, even those fought with the clearest and most straightforward of objectives. The Civil War did not put an end to the terrible plight of blacks in America, though it cost over half a million lives. World War II ended with the Soviet Union in control of half of Europe and opened the way to another four decades of superpower confrontation.

When a nation uses its power to shape a world order, rather than merely for self-defense or conquest, the tenuousness of solutions is even more pronounced. Military actions for world order preservation are almost by definition limited both in scope and objectives. World order maintenance requires operating in the gray areas between victory and defeat. The measure of success is often not how wonderful the end result is, but whether the unsatisfying end result is better or worse than the outcome if there had been no action. To insist on outcomes that always achieve maximum ends at minimal cost is yet another form of escapism.

Today, however, Americans seem overwhelmed by the difficulty and complexity of it all. They yearn to return to what Niebuhr called “the innocency of irresponsibility,” or at least to a normalcy in which the United States can limit the scope of its commitments. In this way America has perhaps returned to the mood of the 1920s. There is a difference, however. In the 1920s, it was not America’s world order that needed shoring up. Americans felt, mistakenly as it turned out, that it was Britain’s and Europe’s job to preserve the world order they had created. Today, it is America’s world order that needs propping up. Will Americans decide that it matters this time, when only they have the capacity to sustain it?

You never miss the water ’til the well runs dry, or so the saying goes. One wonders whether Americans, including their representatives and their president, quite understand what is at stake. When President Obama first took office five years ago, Peter Baker of The New York Times reported that he intended to deal “with the world as it is rather than as it might be.” It is a standard realist refrain and has been repeated time and again by senior Obama officials as a way of explaining why he decided against pursuing some desirable but unreachable “ideal” in this place or that. What fewer and fewer seem to realize, however, is that the last 70 years have offered Americans and many others something of a reprieve from the world “as it is.”

Periods of peace and prosperity can make people forget what the world “as it is” really looks like, and to conclude that the human race has simply ascended to some higher plateau of being. This was the common view in Europe in the first decade of the twentieth century. At a time when there had not been a war between great powers in 40 years, or a major Europe-wide war in a century, the air was filled with talk of a new millennium in which wars among civilized nations had become impossible. Three-quarters of a century and two world wars and a cold war later, millennial thoughts return. Studies cited by Fareed Zakaria purport to show that some “transformation of international relations” has occurred. “Changes of borders by force” have dropped dramatically “since 1946.” The nations of Western Europe, having been responsible for two new wars a year for 600 years, had not even started one “since 1945.” Steven Pinker observes that the number of deaths from war, ethnic conflict, and military coups has declined—since 1945—and concludes that the human race has become “socialized” to prefer peace and nonviolence.

The dates when these changes supposedly began ought to be a tip-off. Is it a coincidence that these happy trends began when the American world order was established after World War II, or that they accelerated in the last two decades of the twentieth century, when America’s only serious competitor collapsed? Imagine strolling through Central Park and, after noting how much safer it had become, deciding that humanity must simply have become less violent—without thinking that perhaps the New York Police Department had something to do with it.

In fact, the world “as it is” is a dangerous and often brutal place. There has been no transformation in human behavior or in international relations. In the twenty-first century, no less than in the nineteenth and twentieth centuries, force remains the ultima ratio. The question, today as in the past, is not whether nations are willing to resort to force but whether they believe they can get away with it when they do. If there has been less aggression, less ethnic cleansing, less territorial conquest over the past 70 years, it is because the United States and its allies have both punished and deterred aggression, have intervened, sometimes, to prevent ethnic cleansing, and have gone to war to reverse territorial conquest. The restraint showed by other nations has not been a sign of human progress, the strengthening of international institutions, or the triumph of the rule of law. It has been a response to a global configuration of power that, until recently, has made restraint seem the safer course.

A sense of futility, today as much as in the 1920s and 1930s, is both an invitation and a justification for a return to normalcy.

When Vladimir Putin failed to achieve his goals in Ukraine through political and economic means, he turned to force, because he believed that he could. He will continue to use force so long as he believes that the payoff exceeds the cost. Nor is he unique in this respect. What might China do were it not hemmed in by a ring of powerful nations backed by the United States? For that matter, what would Japan do if it were much more powerful and much less dependent on the United States for its security? We have not had to find out the answers to these questions, not yet, because American predominance, the American alliance system, and the economic, political, and institutional aspects of the present order, all ultimately dependent on power, have mostly kept the lid closed on this Pandora’s box.

Nor have we had to find out yet what the world “as it is” would do to the remarkable spread of democracy. Skeptics of “democracy promotion” argue that the United States has often tried to plant democracy in infertile soil. They may be right. The widespread flowering of democracy around the world in recent decades may prove to have been artificial and therefore tenuous. As Michael Ignatieff once observed, it may be that “liberal civilization” itself “runs deeply against the human grain and is achieved and sustained only by the most unremitting struggle against human nature.” Perhaps this fragile democratic garden requires the protection of a liberal world order, with constant feeding, watering, weeding, and the fencing off of an ever-encroaching jungle. In the absence of such efforts, the weeds and the jungle may sooner or later come back to reclaim the land.

One wonders if even the current economic order reflects the world “as it is.” A world in which autocracies make ever more ambitious attempts to control the flow of information, and in which autocratic kleptocracies use national wealth and resources to further their private interests, may prove less hospitable to the kind of free flow of commerce the world has come to appreciate in recent decades.

In fact, from the time that Roosevelt and Truman first launched it, the whole project of promoting and defending a liberal world order has been a concerted effort not to accept the world “as it is.” The American project has aimed at shaping a world different from what had always been, taking advantage of America’s unique situation to do what no nation had ever been able to do. Today, however, because many Americans no longer recall what the world “as it is” really looks like, they cannot imagine it. They bemoan the burdens and failures inherent in the grand strategy but take for granted all the remarkable benefits.

Nor do they realize, perhaps, how quickly it can all unravel. The international system is an elaborate web of power relationships, in which every nation, from the biggest to the smallest, is constantly feeling for shifts or disturbances. Since 1945, and especially since 1989, the web has been geared to respond primarily to the United States. Allies observe American behavior and calculate America’s reliability. Nations hemmed in or threatened by American power watch for signs of growing or diminishing power and will. When the United States appears to retrench, allies necessarily become anxious, while others look for opportunities.

In recent years, the world has picked up unmistakable signals that Americans may no longer want to carry the burden of global responsibility. Others read the polls, read the president’s speeches calling for “nation-building at home,” see the declining defense budgets and defense capabilities, and note the extreme reticence, on the part of both American political parties, about using force. The world judges that, were it not for American war-weariness, the United States probably would by now have used force in Syria—just as it did in Kosovo, in Bosnia, and in Panama. President Obama himself recently acknowledged as much when he said, “It’s not that it’s not worth it. It’s that after a decade of war, you know, the United States has limits.” Such statements set the web vibrating. In East Asia, nations living in close proximity to an increasingly powerful China want to know whether Americans will make a similar kind of calculation when it comes to defending them; in the Middle East, nations worried about Iran wonder if they will be left to confront it alone; in Eastern Europe and the Baltic states, American security guarantees are meaningless unless Americans are able and willing to meet them.

Are they? No one has taken a poll lately on whether the United States should come to the defense of its treaty allies in the event of a war between, say, China and Japan; or whether it should come to the defense of Estonia in a Ukraine-like conflict with Russia. The answers might prove interesting.

Meanwhile, the signs of the global order breaking down are all around us. Russia’s invasion of Ukraine and seizure of Crimea was the first time since World War II that a nation in Europe had engaged in territorial conquest. If Iran manages to acquire a nuclear weapon, it will likely lead other powers in the region to do the same, effectively undoing the nonproliferation regime, which, along with American power, has managed to keep the number of nuclear-armed powers limited over the past half century. Iran, Saudi Arabia, and Russia are engaged in a proxy war in Syria that, in addition to the 150,000 dead and the millions displaced, has further destabilized a region that had already been in upheaval. In East Asia, nervousness about China’s rise, combined with uncertainty about America’s commitment, is exacerbating tensions. In recent years the number of democracies around the world has been steadily declining, while the number of autocracies grows. If these trends continue, in the near future we are likely to see increasing conflict, increasing wars over territory, greater ethnic and sectarian violence, and a shrinking world of democracies.

How will Americans respond? If the test is once again to be “national interests” narrowly construed, then Americans may find all of this tolerable, or at least preferable to doing something to stop it. Could the United States survive if Syria remains under the control of Assad or, more likely, disintegrates into a chaos of territories, some of which will be controlled by jihadi terrorists? Could it survive if Iran acquires a nuclear weapon, and if in turn Saudi Arabia, Turkey, and Egypt acquire nuclear weapons? Or if North Korea launches a war on the South? Could it survive in a world where China dominates much of East Asia, or where China and Japan resume their old conflict? Could it survive in a world where Russia dominates Eastern Europe, including not only Ukraine but the Baltic states and perhaps even Poland? Of course it could. From the point of view of strict “necessity” and narrow national interest, the United States could survive all of this. It could trade with a dominant China and work out a modus vivendi with a restored Russian empire. Those alarmed by such developments will be hard-pressed, as Roosevelt was, to explain how each marginal setback would affect the parochial interests of the average American. As in the past, Americans will be among the last to suffer grievously from a breakdown of world order. And by the time they do feel the effects, it may be very late in the day.

Looking back on the period before World War II, Robert Osgood, the most thoughtful of realist thinkers of the past century, discerned a critical element missing from the strategic analyses of the day. Mere rational calculations of the “national interest,” he argued, proved inadequate. Paradoxically, it was the “idealists,” those who were “most sensitive to the Fascist menace to Western culture and civilization,” who were “among the first to understand the necessity of undertaking revolutionary measures to sustain America’s first line of defense in Europe.” Idealism, he concluded, was “an indispensable spur to reason in leading men to perceive and act upon the real imperatives of power politics.” This was Roosevelt’s message, too, when he asked Americans to defend “not their homes alone, but the tenets of faith and humanity on which their churches, their governments, and their very civilization are founded.”

Perhaps Americans can be inspired in this way again, without the threat of a Hitler or an attack on their homeland. But this time they will not have 20 years to decide. The world will change much more quickly than they imagine. And there is no democratic superpower waiting in the wings to save the world if this democratic superpower falters.