Middle powers and Thucydides Trap

Middle powers Corinth and Corcyra were central to the chain of crises that dragged Athens and Sparta into war, while Syracuse helped turn the conflict decisively against Athens.

During Trump’s visit to Beijing, Xi Jinping brought up the “Thucydides Trap.” Media outlets reported that Xi raised the concept directly in discussions about U.S.-China rivalry and Taiwan. Now there ain’t nobody going to explain this from the middle power point of view, so let’s give it a go.

The Thucydides Trap is the idea that rising powers and dominant powers drift toward conflict through fear, rivalry, alliance pressures, and repeated crises. Graham Allison popularized it in his 2017 book Destined for War: Can America and China Escape Thucydides’s Trap? He applied the ancient Athens–Sparta dynamic to modern U.S.–China relations, and warned that structural tensions between a rising China and an established United States could produce conflict unless carefully managed.

What is rarely discussed is the fact that the real genius of Thucydides was not simply his description of great powers but rather his understanding of how great-power tension spreads through middle powers. Alliances, dependencies, fears, ambitions, and local calculations transform rivalry into systemic conflict.

The middle powers are not background characters in the “Thucydides Trap”. They are the sparks, buffers, brokers, and battlegrounds through which great power rivalry is intensified, restrained, and ultimately decided.

If we’re willing to let our imaginations stretch for just a few moments, it’s not too difficult to see middle powers in U.S.-China rivalry as strange allusions to those states between Athens and Sparta in Thucydides accounts.

Australia could be Corinth; South Korea could be Corcyra; and Canada could be Syracuse.

Corinth was not the strongest power, but it was one of the loudest advocates for confrontation with Athens. A proud maritime-commercial state deeply tied to Spartan power, Corinth constantly pressured Sparta to act more aggressively against Athenian expansion. It feared economic displacement, strategic encirclement, and declining status within the Greek order.

Australia increasingly plays a similar role inside the American alliance system. No U.S. ally has embraced the language of strategic confrontation with China more enthusiastically. Canberra speaks of existential struggle, democratic values, regional balancing, and strategic deterrence with almost missionary zeal. It has tied itself tightly to Anglo-American military integration through arrangements like AUKUS, expanded basing access, intelligence cooperation, and long-range strike capabilities.

Like Corinth, Australia is both anxious and energetic. It fears abandonment by the hegemon, yet simultaneously pushes the hegemon toward firmer confrontation. The irony is that Corinth itself eventually suffered enormously from the war it helped intensify.

South Korea, meanwhile, increasingly resembles Corcyra — trapped between systems.

In Thucydides’ account, Corcyra was strategically valuable not because it was dominant, but because both sides feared what its alignment might mean. Its internal divisions and external balancing became entangled in the larger rivalry between Athens and Sparta.

South Korea today sits in a remarkably similar position between the U.S.-led maritime alliance system and the increasingly China-centered economic order emerging in Asia. Seoul depends upon the United States for security guarantees, intelligence, and strategic protection. Yet its economy remains deeply integrated with China-centered supply chains, markets, and industrial ecosystems.

Like Corcyra, South Korea’s greatest challenge is not choosing sides once and for all. It is surviving prolonged systemic rivalry without becoming the battleground upon which others resolve their disputes.

This is why South Korean foreign policy often appears contradictory to outside observers. Seoul simultaneously deepens trilateral security cooperation with the U.S. and Japan while attempting to stabilize relations with Beijing. It participates in alliance structures while hesitating to fully ideologize the rivalry. Critics call this ambiguity. In reality, it is strategic survival.

Then there is Canada—increasingly resembling Syracuse.

Syracuse entered the Peloponnesian War later, after years of relative insulation from the core Greek rivalry. Wealthy, distant, and somewhat protected by geography, it initially avoided the direct pressures consuming mainland Greece. But when Athens eventually turned westward during the disastrous Sicilian Expedition, Syracuse suddenly found itself at the center of systemic conflict.

For decades, Canada similarly benefited from distance, insulation, and the assumption that geography itself provided security. Protected by the continental shield of American power, Ottawa could afford to treat hard geopolitics as secondary to trade, norms, institutions, and domestic social management.

But geography is becoming less protective in an age of Arctic competition, continental missile vulnerability, technological fragmentation, and deteriorating U.S. political stability. Canada increasingly finds itself drawn into a harsher strategic environment it spent decades assuming it could avoid. The danger for Syracuse was not simply external attack. It was complacency. It mistook temporary distance from the center of rivalry for permanent immunity from it.

So how did the ‘Thucydides Trap’ impact Corinth, Corcyra, and Syracuse? Corinth and Corcyra were central to the chain of crises that dragged Athens and Sparta into war, while Syracuse helped turn the conflict decisively against Athens.

Corinth was one of Sparta’s key allies and played a major role in escalating tensions with Athens. Corinth feared Athenian expansion and growing naval influence would undermine its own commercial and regional power. Angry at what it saw as Athenian interference in its affairs, Corinth pressured Sparta to act more aggressively, helping transform a series of local disputes into a wider systemic confrontation between Athens and Sparta.

Corcyra (modern Corfu) became trapped between larger powers during a dispute with Corinth, its colonial parent city. Corcyra sought Athenian protection against Corinthian pressure, while Athens saw strategic value in Corcyra’s powerful navy. The resulting alliance deepened Spartan fears that Athens was expanding uncontrollably. What began as a quarrel between smaller states thus became entangled in the broader rivalry that led to the Peloponnesian War.

Syracuse became central later in the war when Athens launched the disastrous Sicilian Expedition. Athens hoped conquering Syracuse would expand its empire and cut Spartan influence in the west. Instead, Syracuse resisted fiercely, received Spartan support, and destroyed the Athenian expeditionary force. The defeat crippled Athens militarily and financially, marking a turning point in Sparta’s eventual victory.

Corinth set the trap, Corcyra sprang it, and Syracuse sealed Athens’ fate.

This is the central lesson of Thucydides for middle powers. The real danger in periods of hegemonic transition is not merely choosing the wrong side. It is misunderstanding your own role in the system itself.

Some middle powers become enthusiastic advocates for confrontation. Some attempt delicate balancing between rival systems. Some assume distance will protect them indefinitely. But all are ultimately shaped by the structural tensions flowing through the international order.

Now, we’ve only covered three middle powers. If we start thinking about Iran, Mongolia, Poland, Indonesia, Ukraine, and Vietnam, we have an array that makes the Peloponnesian War collection of Megara, Miletus, Rhodes, Chios, Lesbos, Epidamnus, Potidaea, Boetotia, Thasos, Byzantium, Cyzicus, Ephesus, and Aegina look simple.

Thucydides understood something many modern international relations theorists still struggle to grasp: great-power competition is not experienced most intensely by the great powers themselves—it is experienced most intently by the middle powers between them.

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