The 20th Century’s Lessons for Our New Era of War – Foreign Policy

This article is an excerpt from The Eurasian Century: Hot Wars, Cold Wars, and the Making of the Modern World by Hal Brands (W. W. Norton, 320 pp., $29.99, January 2025).

There was nothing simple about this. Preventing global war was arduous, morally troubling work. It required learning the apocalyptic absurdities of nuclear deterrence. It involved fighting bloody “limited” conflicts, going to the brink over Cuba and Berlin, and preparing incessantly for a confrontation the United States and its allies hoped never to fight. The long great-power peace of the postwar era didn’t just happen; it was the payoff of a decades-long effort to make the military balance favor the free world. An important lesson, then, is that a cold war is the reward for deterring a hot one.

As the citizens of Ukraine can attest, high-intensity warfare is not some artifact of a receding past. As Israel has rediscovered, technological superiority is no guarantee against the most lethal forms of military surprise. In a Western Pacific menaced by Chinese power, the peace grows fragile. Don’t assume that revisionist states won’t simply try to seize their objectives—or that democracies must always prevail in tests of strength. The price of peace, in the present era, will be another long military competition.

Deterrence on NATO’s eastern front will require well-armed frontline states that can put up a real fight, forward-deployed alliance forces that can slow a Russian onslaught, and a NATO that can surge power into hard-to-access areas while keeping the Kremlin from using nuclear coercion to impose a settlement on its terms. That’s difficult but doable for the mightiest, most experienced alliance. The situation is more daunting in the Pacific, where the United States has no region-wide alliance, and where China’s buildup is threatening to confront America with a choice between fighting and losing a war to save Taiwan, and simply not fighting at all.

“Taiwan is like two feet from China,” President-elect Donald Trump remarked during his first term in 2019. “If they invade, there isn’t a fucking thing we can do about it.” Fortunately, securing the peace in East Asia isn’t as hopeless as the map might make it seem. The fundamental asymmetry favoring China is proximity. The fundamental asymmetry favoring its enemies is that denial is easier than control, especially when control means projecting power over large bodies of water. Forcibly seizing Taiwan, with its oceanic moat and rugged terrain, would take one of the most complex military operations in history. The outlines of a strategy for defeating—or better yet, deterring—such an assault are readily apparent.

They include turning Taiwan into a prickly porcupine, bristling with arms and ready to fight until the end; flipping geography against Beijing by making the first island chain a series of strongpoints stocked with anti-ship missiles and patrolled by lethal attack submarines, backed by a second island chain studded with U.S. air power, logistical capabilities, and long-range precision-strike aircraft; ensuring that the Pentagon has ample magazines of the torpedoes, missiles, and other munitions needed to decimate a blockade squadron or invasion fleet; and preparing to cut off China’s imports of energy and other key materials through a blockade centered on distant chokepoints that the U.S. Navy can control.

A man stands at the edge of anti-tank fortifications in Kinmen, Taiwan, on April 9, 2023, as he takes photos of the sunset over the Chinese city of Xiamen, which is located less than three miles away. Chris McGrath/Getty Images

They include, also, knitting Washington’s regional relationships into something more capable of, and explicitly committed to, a coalition defense; readying, with other advanced democracies, severe economic and technological punishments should Beijing attack; and integrating allied defense industrial bases into a 21st-century arsenal of democracy that can sustain a long conflict. Finally, and most uncomfortably, deterrence requires possessing a credible ability to fight a limited nuclear war in the Western Pacific, if only so that China doesn’t feel emboldened, as its own arsenal matures, to use nuclear coercion to prevent the United States from intervening at all.

This formula can deny China an easy victory, while exploiting U.S. advantages—alliances, global power-projection, economic and technological leverage—to make the conflict devastating, destabilizing, and existentially dangerous for the regime of Chinese President Xi Jinping. It all sounds awful, but preparing for the unthinkable is the best way of ensuring it never occurs. It is heartening, then, that Washington and other countries are making real, in some ways historic, progress in all these areas—and terrifying that they often seem to be moving in slow motion as Beijing races to ready for a fight. “For almost 20 years we had all of the time and almost none of the money,” U.S. Army Chief of Staff George Marshall wrote as Adolf Hitler steamrolled Europe. “Today we have all of the money and no time.” The United States will eventually pay to keep key regions out of hostile hands. Far better to balance early than to balance late.

Any balancing effort begins at home, so it has become obligatory, in discussions of foreign policy, to say that America must get its own house in order. Like most clichés, it’s partly true. One thing the anti-interventionists of earlier eras got right is that America’s power is no greater than the vibrancy of its economy, society, and democracy. The twist is that if the United States had insisted on perfecting itself before going abroad to fight two world wars and a cold war in the 20th century, the world would be run by regimes less paralyzed by their imperfections. Global involvement can, in fact, be an impetus to domestic renewal: Having enemies at the gates concentrates the mind on weaknesses within the walls.

This effect endures. Washington’s turn toward great-power competition has already produced historic outlays in semiconductor manufacturing and other strategic priorities with domestic payoffs.

There is, however, a less-noticed aspect of the notion that foreign policy begins at home: The Western Hemisphere is the forgotten, vital theater of Eurasian competition. Alfred Thayer Mahan, the great American naval strategist, understood that the United States had to secure the Panama Canal and the Caribbean before it could patrol the oceans. Or, as international relations scholar Nicholas Spykman put it, the United States eventually accrued “power to spare” for intervention in distant theaters because it was supreme within its own. Hemispheric immunity and global activism went hand in hand. America’s enemies understood this, too; from the Zimmermann telegram that offered Imperial Germany’s support for a Mexican invasion of the United States in 1917 to the Cuban missile crisis, every struggle of the last century saw Eurasian powers stir the pot of political instability and anti-Americanism in Latin America, in hopes of putting Washington off-balance by putting it on the defensive in its own backyard.

U.S. missiles stand ready for action on George Smathers Beach in Key West, Florida,  on Oct. 28, 1962, during the Cuban missile crisis. Bettmann Archive/Getty Images

Today’s Eurasian powers know the playbook. Russia and Iran have supported illiberal populists around the Caribbean basin. China is inserting itself into Latin American economies, infrastructure, and technological networks, while laying the groundwork for a larger security presence from Argentina to Cuba. One doesn’t have to think it is October 1962 all over again to understand the implications. Just as countries that dominate their home regions will have greater scope to reach into the Western Hemisphere, a presence in that hemisphere can distract and hobble a superpower used to ranging overseas. The logic of the Monroe Doctrine—the idea that the United States cannot let hostile powers or hostile ideologies hold sway in the Western Hemisphere—remains as valid as ever, even if the language needlessly offends sovereign states to Washington’s south.

Another epoch of competition foretells another effort to keep U.S. rivals from setting up shop there. Don’t be shocked if Washington eventually uses some of the same sharp-edged tools, from economic coercion to covert intervention, that it deployed in the Cold War; even enlightened democracies resort to hard measures in hard times. Yet the more the United States can pursue a negative objective—strategic denial of the Western Hemisphere to its adversaries—with a positive program of regional cooperation, the more effective it will be.

A degree of deglobalization vis-à-vis China creates opportunities for deeper regionalization of trade and manufacturing in the Western Hemisphere. Investments in sustaining the region’s strained democracies and rebuilding long-neglected relations with its militaries are good value amid intensifying international tensions. Most ambitiously, a stronger North American community—in which the United States, Canada, and Mexico are increasingly fused together economically and technologically—can counterbalance China’s forbidding heft. That’s an imposing and politically challenging agenda. But the tighter the bonds of integration within the Americas, the greater the power Washington can wield in a fragmenting world.

Much of this paints a grim portrait of the future—a future of high-octane rivalry as far as the eye can see. The Eurasian supercontinent’s vital regions and adjoining seas will see contests in “containment and counter-containment,” as China’s defense minister said in 2021. The global economy will be reshaped by the threat of war and the pressures of competition. Proxy conflicts and crises will become more common; the United States and other defenders of the prevailing order will look to punish their rivals’ missteps. Foreign policy will become a starker, more remorseless enterprise, as democratic societies rediscover that the only way to preserve a system that is liberated from the worst patterns of geopolitics is to master the ruthless practice of geopolitics in dealing with those who would bring about its demise. That may not sound appealing. But remember: Eurasian struggles are opportunities for creation.

The 20th century was a monument to humanity’s worst impulses. It was also the cradle of the freest, most flourishing age humanity has known. The worst of times led directly to the best of times; the creation of the liberal order was how a global superpower and its allies wrenched history off its destructive path. Today, old dangers are reappearing in new forms. The world no longer seems so safe from great-power war, autocratic ascendancy, the deliberate and large-scale victimization of civilians, and other scourges that characterized a long era of conflict. Keeping these specters at bay will demand another era of creation.

Most international orders are “orders of exclusion”; they suppress those on the outside by building norms, institutions, and architectures of cooperation among those within. Whether the problem is deterring aggression, defeating political warfare, or foreclosing a future in which technology entrenches and empowers tyranny, the solution involves adapting and improving the existing system that has served so many countries so well.

U.S. soldiers watch as NATO paratroopers drop from a U.S. Air Force Hercules during a joint exercise at Bezmer airfield in Germany on July 18, 2017. Dimitar Dilkoff/AFP via Getty Images

A coalition that holds the line in crucial theaters will be one in which a globe-spanning group of countries has buttressed the norm against territorial conquest by pulling itself together—militarily, economically, diplomatically—as never before. A free-world alliance that outpaces its enemies technologically will be one that has reached new frontiers of innovation by pooling its resources and creativity in unprecedented ways. A group of democracies that defends its values will be one that has forged better methods for tackling transnational corruption and repression. A coalition that has competed effectively for global influence will be one that has embraced innovative forms of institution-building—of the sort seen with the Quad, AUKUS, and other initiatives—that adapt the architecture of international cooperation to match the most pressing modern challenges. The presence of enemies, as the British geographer Halford Mackinder once wrote, can ultimately have “stimulative” effects. The proper response to a world riven by conflict is not to junk the liberal order. It is to strengthen that order against the actors trying to bring it down.

Achieving any of this means heeding a final lesson: There is no such thing as destiny. The history of the modern era might make one think Eurasian gambits are doomed to fail—that seeking hegemony is tantamount to committing strategic suicide. After all, from Mackinder’s time onward, every Eurasian challenger was defeated, because every challenger provoked a pack of enemies that killed its prey. The 20th century led not, as Mackinder worried, to a nightmarish “empire of the world” but to a brighter existence for much of humanity. The moral arc of the universe may be long, the saying goes, but perhaps it does bend toward justice.

It’s a pleasing and profoundly dangerous notion. Each fight for Eurasia could have gone differently; the good guys didn’t have to come out on top. In World War I, a determined German Empire might plausibly have defeated the Allies and remade the system. In World War II, there were many moments when a different decision or personality might have changed the course of events. In the early Cold War, it wasn’t fate but urgent, improvised policies that saved the day. There is no law of nature that expansion must fail and tyranny must be vanquished. There is no guarantee that history takes the path of progress.

Indeed, the idea of progress would have seemed absurd for much of the last century, when it appeared that modernity had produced ever worse forms of warfare and ever more toxic types of tyranny. Progress is the product of power, deployed for constructive purposes. The moral arc of the universe was exactly what America and its allies made of it—just as the outcome of the current Eurasian struggle will hinge on their choices and commitment in years ahead.

There’s no inherent reason that they can’t find the winning formula. Eurasia’s revisionist powers are already running into resistance; they are suffering from the pathologies of their rulers and regimes. The prospect that these countries may be traveling a road that ends in encirclement and exhaustion isn’t lost on shrewd observers in autocratic capitals. Even Chinese military analysts admit that countries that take on America and its many allies typically pay an awful price. “Don’t think of Imperial America as a ‘paper tiger,’” wrote Dai Xu, a senior People’s Liberation Army officer, in 2020. “It’s a ‘real tiger’ that kills people.”

If Washington and its friends can consistently stymie this set of Eurasian ambitions, if they can bolster the order their enemies aim to weaken, if they can show that rivalry brings more pain than profit for revisionist regimes, then perhaps policies or politics in Moscow, Tehran, and Beijing will eventually mellow. As the resolution of the Cold War reminds us, countries—even ideologically radical ones—do sometimes reconcile themselves to realities they cannot change.

But don’t take anything for granted. Outlasting the Soviet Union required a 40-year struggle pervaded by threats of Armageddon. Other aspiring hegemons did dreadful damage before they fell. Today’s Eurasian powers will try to smash, subvert, or seduce the countries around them. They will hope an overseas superpower that has settled three prior confrontations stumbles in a fourth.

History suggests the odds are against them. But history also shows that surprises happen and democratic dominance is not assured. Geography shapes but strategy decides: That’s the most crucial insight the Eurasian century offers.