America Doesn’t Need to Fear the “Thucydides Trap”

During their May 2026 summit, Chinese President Xi Jinping challenged President Donald Trump with a warning of the “Thucydides trap.” While American leaders can learn much from the ancient Peloponnesian War, the lessons run counter to Xi’s purposes. Rather than a rigorous analysis of a war between a declining hegemon and a rising upstart, Thucydides’ tragic history recounts the Athenian hubris and Spartan stubbornness that brought down the ancient Greek city-states. The moral of the story?: Beware Chinese Communists bearing Greek gifts.

Xi invoked the greatest of ancient historians to warn against an American military defense of Taiwan. It seems an analogy too far to compare the twenty first century rivalry between the United States and China to the War between Athens and Sparta that took place from about 431 to 400 B.C. Nevertheless, scholars of grand strategy often begin with the Peloponnesian War. They use the Melian dialogue to introduce students to realism: in 416 B.C., the invading Athenians declare to the defiant inhabitants of Melos that “the strong do what they can and the weak suffer what they must.” During the Cold War, scholars compared the superpower rivalry between the U.S. and the U.S.S.R. to a Greek world as divided between a regimented society whose army controlled the land (Sparta) and a commercial republic based on sea power (Athens). During the Afghanistan and Iraq Wars, critics claimed that the United States had engaged in misguided military adventures just as Athens overextended itself in its disastrous 415-413 B.C. Sicilian expedition.

Now, some strategists and Chinese leaders (apparently) believe that Thucydides can teach Washington how to approach its Asian rival. Not just Xi, but American scholars warn that the U.S.-China rivalry could trigger a disastrous war, much as Athens and Sparta waged a destructive war that ultimately ended the dominant power of both city-states. Some strategists in the United States have fixated on Thucydides’ explanation of the war’s true cause. He did not blame inherent human nature for causing war. He did not lay the blame at the feet of the city-state as an organizational form. Instead, he seemed to blame rapid changes in the balance of power within an anarchic international system. Thucydides writes in Chapter I of the first Book of his history:

The real cause I consider to be the one which was formally

most kept out of sight. The growth of the power of Athens, and the

alarm which this inspired in Lacedaemon, made war inevitable.

Noted Harvard political scientist and former Obama national security official Graham Allison has labeled this “the Thucydides trap.”

The trap beckons a dominant power to launch a pre-emptive war against a rising nation. Suppose a leading nation, such as Sparta in 431 B.C., or Great Britain in 1914, has enjoyed a position of hegemonic leadership in the world. It has provided enforced stability while also enjoying the benefits of empire. A rising nation, however, whether Athens after the victory over the Persians or Wilhelmine Germany after unification, threatens the leading nation’s primary position. Rather than waiting for a future conflict when the rising power may have closed the gap in power, the hegemon strikes first while it still commands military and economic advantages. As Thucydides observes, the “alarm” in Sparta over the “growth of the power of Athens” made war “inevitable.” Some, such as Allison’s project at the Harvard Kennedy School of Government, argue that Britain’s entry into World War I was intended to arrest Germany’s rise.

There are several reasons to doubt the analogy between the Peloponnesian War and the U.S.-China rivalry. This is not to say that we cannot learn from studying Thucydides. The technologies and strategies of war may change, but human nature remains constant. War has continued throughout human history, even as ideologies, empires, and military innovations have come and gone. Perhaps Thucydides shows that war remains a permanent feature of the human condition because certain characteristics of human beings and their societies do not change. Berkeley political science great Kenneth Waltz famously argued that explanations for war that sought the answer in individual human traits or in the design of nation-states were flawed; instead, the answer lay in the fundamentally anarchic nature of the international system. Thucydides certainly provides much evidence to support Waltz’s theory, even though the Greeks shared far more history, language, religion, and ethnicity than the nations of the world today do.

But it would be a mistake to understand Thucydides as providing evidence for the more precise claim that hegemonic powers have a dangerous incentive to launch preventive wars. First, it is not obvious that Thucydides’ account of the Peloponnesian War even fits the thesis that we moderns have named after him. Scholars have long debated the origins of the great war that destroyed the ancient Greek world, but it does not appear that Spartan belief in prevention bears full responsibility. Sparta did not act as if it were the dominant hegemon in the Greek world. The Lacedaemonians may have been critical to the war against the Persians, but it was the Athenian navy, led by Themistocles, that won the battle of Salamis and sealed the victory. By the time of the war’s outbreak, Athens may already have equaled Sparta, if not in fact held the dominant position in the Greek world. As Victor Davis Hanson has observed, Athens had 300,000 people, 300 warships, and an alliance of 200 city-states paying tribute; Sparta had an army of 10,000, a population of 250,000 serfs, and control over the city-states of the Peloponnese. If anyone started the war, it was Athens, which courted war against Sparta’s ally, Corinth, and sought to impose trade restrictions on neutral cities.

Second, even if the Peloponnesian War mapped onto the U.S.-China rivalry, strategists of the Allison variety may have the Athenian and Spartan roles exactly backward. Athens and Sparta seemed to occupy the polar opposites of the Greek world. Athens, as Thucydides underscored, had risen due to its dynamic, acquisitive, commercial character. It boasted the largest fleet in Greece, a vast maritime trading empire, and an unruly democracy. Ruled by a monarchy, Sparta, by contrast, cultivated a stolid, militarist society, divided into a warrior elite bred from birth and a population of helots. During the Cold War, observers often compared the United States, with its control of the seas and the air, its broad network of alliances, and its liberal democracy, to Athens. The Soviet Union, with its vast ground forces, totalitarian dictatorship, and command economy, naturally stood in for the Spartans. Despite its striking arms buildup and more advanced economy, China’s power similarly remains rooted in massive ground forces and an oppressive, regimented political system. Beijing’s massive naval and missile buildup aims to give it regional superiority in Asia, but it cannot project power globally as only the United States can. Faced with a shrinking population and a stalling economy, China may well be the Sparta of today; it may see its military power declining in the future and a window closing to take advantage of its military superiority in East Asia.

If any nation today takes after Athens, it is the United States. The American economy outpaces that of Europe – since 2008, when the U.S. and European Union economies were roughly equal, U.S. GDP is now 1.5 times larger; per capita European GDP has fallen in the same period from 76 percent to 50 percent of US per capita GDP. The United States has maintained an innovative, diverse economy that has produced stunning productivity gains, allowed high technology to flourish, and leads the world in the cutting-edge sectors of artificial intelligence, digital services, and space. The United States has developed technologies that have allowed it to become energy independent. It maintains deep and broad markets that support innovation and new firms. China has instead grown by dominating low-end manufacturing, supported by a vast pool of cheap labor, and by stealing Western technology. While its technological innovation may become competitive, especially where Beijing decides to concentrate resources, such as in artificial intelligence, China’s economy still remains subject to the rigid political control of the Chinese Communist Party.

Third, the Thucydides trap may explain little beyond its own time. The rise of a new great power, of course, will introduce instability into an existing order. Nations that increase their economic resources and develop their militaries will pursue broader interests beyond pure self-defense. This may bring the rising powers into conflict with other nations, but that alone need not trigger war. Historians will make comparisons between Athens and Sparta and the rise of France in the sixteenth ^h century, Great Britain in the eighteenth century, and the United States, Germany, Japan, and Russia/Soviet Union in the nineteenth and twentieth centuries. But defining the rising power, as we can see from multiple examples in the nineteenth and twentieth Centuries, is difficult, and the link between a hegemon’s fears of a change in the balance of power and the outbreak of war is unclear. Take, for example, World War I. There may be some evidence that the Britain sided with France to contain Germany, which had challenged British sea dominance. But there is also historical evidence that Germany believed it had a limited window for war because of the rise of Russian military power on its Eastern Front. Or consider Japan. Japan may have been the rising power in the early twentieth century, but Tokyo, not Moscow, launched the 1904-1905 war with a surprise attack on the Russian Pacific fleet. Japan launched another surprise attack on the U.S. Pacific fleet at Pearl Harbor on December 7, 1941, “a date that will live in infamy.” But again, the rising power and not the dominant one unleashed war.

The Thucydides trap may not be about preventive war, but about great powers defeating themselves by drawing the wrong analogies from the past. During the Cold War, critics of American national security policy raised the Peloponnesian War to claim that the United States would inevitably lose. We were like Athens in that our commercial, dynamic nature would lead other nations to fear us. We were like Athens in that our democratic character would generate an instability and lack of commitment that would undermine the pursuit of long-term strategy. Critics argued that the Soviet Union, mirroring Sparta, had the discipline and focus to outlast us. Just as Athens broke on the failure of its Sicilian Expedition, so too would the American Empire fail after the retreat from Vietnam.

Of course, the Cold War did not turn out that way. The unruly democracy prevailed after all. The innovative, dynamic, and acquisitive Americans generated such striking productivity and innovation that the latter-day Spartans gave up without firing a shot. Thucydides may have shown that, in ancient Greece, the acquisitive democracy suffered from such political instability that it could not win a two-decade war. But in the twentieth century, the constitutional democracy of the United States, where power remained shared among three branches of government, and was supported by a federalism that decentralized authority over domestic matters, could commit to the long-term strategy of containment that prevailed against the Soviet Union. Americans would be wise to return to that history when considering the challenge raised by China today, rather than the mistakes made during a war fought 2,500 years ago.

John Yoo is a senior research fellow at the Civitas Institute, and a distinguished visiting professor at the School of Civic Leadership at the University of Texas at Austin.