The Thucydides Trap: Will the United States and China Go to War?

By Matthew Parish

Wednesday 26 August 2026

There is a peculiar quality to relations between the United States and China in the middle of the 2020s. Both countries insist that they do not want war. Both countries understand that a war between them might be catastrophic. Both possess nuclear weapons, immense conventional armed forces and economies whose prosperity remains, notwithstanding years of attempted decoupling, substantially intertwined. Yet both are preparing with increasing seriousness for the possibility that they might have to fight one another.

This uncomfortable contradiction has acquired a name: the Thucydides Trap.

The expression comes not directly from Thucydides but from the American political scientist Graham Allison, who popularised it to describe a recurrent phenomenon in international relations. When a rising power approaches the strength of an established dominant power, the resulting fear, insecurity and competition may propel the two states towards war — even where neither originally desired it.

The inspiration is Thucydides’s account of the Peloponnesian War between Athens and Sparta in the fifth century BC. Athens had become rich, confident, maritime and increasingly powerful. Sparta was the established military power of the Greek world. Thucydides identified the growth of Athenian power, and the fear this produced in Sparta, as the underlying cause of the war.

Allison examined a series of historical cases in which a rising power challenged an established one and concluded that war had occurred in twelve of sixteen examples. Whether this methodology is persuasive has been extensively debated. Historical analogies are treacherous things. No two periods of history reproduce one another and the selection of sixteen particular cases inevitably involves questions about what counts as a rising power, what counts as an established power and whether particular wars were really caused by transitions in relative strength.

Nevertheless the expression has stuck because it describes something intuitively recognisable about international politics. Great powers tend not to surrender their positions voluntarily. Rising powers tend not to accept indefinitely an international system whose principal rules were devised before they became powerful.

China and the United States therefore seem almost laboratory-designed for Allison’s theory.

Xi Jinping and the Trap

The most interesting feature of the Thucydides Trap is that Xi Jinping himself has repeatedly discussed it.

Xi’s position has never quite been that China and the United States are condemned to fight. Indeed he has argued almost precisely the opposite. In a 2015 speech in Seattle, Xi observed that there was no such thing as an intrinsically existing Thucydides Trap but warned that repeated strategic miscalculations by major countries might create one for themselves. In other words, history does not make war inevitable. Political leaders can nevertheless behave as though it does — and thereby bring about precisely the catastrophe they fear.

In May 2026 Xi returned conspicuously to the idea during his summit with US President Donald Trump in Beijing, asking whether China and the United States could overcome the Thucydides Trap and establish a new paradigm for relations between great powers.

That is an important choice of language. It reveals that China’s leadership is thinking explicitly in terms of historical power transition. Beijing understands that its relationship with Washington is no longer principally about trade deficits, tariffs, intellectual property or even competing political ideologies. It is about the distribution of power in the international system.

The question is whether that recognition makes war more likely or less likely.

There is a respectable argument for optimism. If both sides know that a trap exists, they can take care not to fall into it. Yet there is an equally respectable argument for pessimism. Once political leaders begin viewing every dispute through the prism of an historic struggle for supremacy, otherwise manageable disagreements can acquire existential significance.

A quarrel over a reef becomes a test of American credibility. An arms sale to Taiwan becomes evidence of an American conspiracy to contain China. A Chinese naval exercise becomes preparation for invasion. A semiconductor export restriction becomes economic warfare.

This is how traps are constructed.

China Is Not Nazi Germany

The first requirement for thinking sensibly about the possibility of a Sino-American war is to discard some bad historical analogies.

China is not Nazi Germany. Xi Jinping is an authoritarian nationalist leader but China is not pursuing anything resembling Hitler’s programme of racial-imperial conquest. Beijing has substantial territorial ambitions and disputes with its neighbours but she does not appear to contemplate conquering Japan, India, Australia or the United States.

Nor is China quite the Soviet Union. The Soviet-American confrontation was ideological and comparatively economically segregated. There was remarkably little economic interdependence between the USSR and the United States. China, by contrast, grew rich precisely by participating in an international economic order substantially constructed by the United States and her allies.

The irony is considerable. America’s greatest geopolitical competitor was enriched by the American-led system.

From the late 1970s onwards, China progressively opened herself to foreign capital and international commerce. Western governments generally hoped that economic liberalisation would eventually encourage political liberalisation. China joined the World Trade Organization. Western manufacturers relocated enormous portions of their supply chains to China. American consumers purchased inexpensive Chinese products while China accumulated vast quantities of foreign currency reserves.

For a time everybody seemed to benefit.

Then the assumptions underlying the arrangement began to unravel.

China became richer without becoming Western. The Communist Party did not disappear. Under Xi it became more centralised and authoritarian. China began constructing a formidable navy, expanding her nuclear arsenal, developing sophisticated missiles, investing enormously in artificial intelligence, space technology, cyber capabilities and semiconductor production, and asserting increasingly expansive claims in the seas surrounding her.

Washington gradually concluded that it had not integrated China into an American international order. It had helped create a competitor to that order.

That realisation is the contemporary foundation of the Thucydides problem.

The Taiwan Question

If the United States and China do fight, the most likely cause is Taiwan.

Virtually everything else is negotiable. Tariffs can be altered. Sanctions can be removed. Technology restrictions can be revised. Islands can remain disputed for decades. Diplomatic insults can be forgotten.

Taiwan is different because the competing positions touch the core political legitimacy of both sides.

For the Chinese Communist Party, Taiwan is not merely an island with approximately 23 million inhabitants. It represents the unfinished business of the Chinese Civil War. Beijing regards Taiwan as part of China and reunification as an historic national objective.

For Taiwan, however, decades of separate political development have produced a prosperous democratic society with its own government, armed forces, currency and political identity. Whatever diplomatic formulas may be used, Taiwan functions in most respects as an independent state.

The United States has deliberately maintained ambiguity about what it would do if China attempted to conquer Taiwan. Washington recognises the People’s Republic of China while maintaining extensive unofficial relations with Taipei and supplying Taiwan with the means to defend itself.

This ambiguity has historically been useful. Beijing cannot be certain that attacking Taiwan would avoid American intervention. Taiwan cannot be certain that declaring formal independence would receive American military protection.

Uncertainty deters both parties.

Yet strategic ambiguity becomes more dangerous as military capabilities change.

China’s armed forces are dramatically stronger than they were twenty years ago. The People’s Liberation Army has developed extensive missile forces designed in part to make American intervention in the western Pacific prohibitively costly. China possesses the world’s largest navy by number of vessels, although crude ship counts tell us relatively little about actual combat capability. Meanwhile Taiwan has been attempting to develop a more asymmetric defensive posture, including drones, missiles, mines and dispersed military infrastructure.

The lessons of Ukraine have not gone unnoticed in Taipei. In August 2026 Taiwan conducted its first live-fire exercises involving first-person-view drones as it sought to incorporate lessons from the Ukrainian battlefield.

China has noticed those lessons as well.

The Geography of War

A Sino-American war would be extraordinarily difficult for both sides because geography simultaneously favours and disadvantages China.

China would fight close to home. American forces would operate thousands of kilometres from the continental United States. Chinese missiles could threaten American bases in Japan, Guam and elsewhere. Beijing could concentrate enormous resources around the Taiwan Strait.

Yet crossing approximately 130 kilometres of water and invading a heavily populated island is among the most difficult military operations imaginable.

The Normandy landings of 1944 required extraordinary preparation against an enemy already fighting a gigantic war on several fronts. Taiwan has mountains, dense cities, limited suitable landing areas and an increasingly sophisticated defensive establishment. An amphibious assault would expose Chinese ships to missiles, submarines, aircraft, drones and mines.

Therefore the popular image of thousands of Chinese landing craft suddenly charging across the Taiwan Strait may not represent the most plausible beginning of a crisis. China has alternatives.

It could impose a blockade. It could announce customs inspections. It could occupy one or more of Taiwan’s offshore islands. It could establish exclusion zones under the pretext of military exercises. It could attack communications infrastructure, conduct cyber operations or sever undersea cables. It could attempt to strangle Taiwan economically while leaving Washington with the agonising decision whether to fire the first unmistakable shots.

This grey area between peace and war may be more dangerous than invasion itself.

The South China Sea

Taiwan is not the only potential flashpoint.

China has spent years strengthening its position across the South China Sea, constructing and militarising artificial islands and asserting claims contested by Vietnam, the Philippines, Malaysia, Brunei and Taiwan.

The process continues. In August 2026 satellite imagery indicated that China had completed the first phase of extensive reclamation at Antelope Reef in the disputed Paracel Islands. The emerging artificial island includes a substantial harbour and infrastructure that analysts believe could eventually support significant military operations.

The United States does not accept China’s broad maritime claims and continues to maintain that international waters must remain open.

Here the danger is less that either Beijing or Washington deliberately decides to begin a world war than that something goes wrong.

A Chinese vessel collides with an American or allied ship. An aircraft is shot down. Chinese and Philippine forces exchange fire. American treaty obligations are invoked. Each side mobilises to demonstrate resolve. The other interprets mobilisation as preparation for attack.

The First World War should worry us at least as much as the Peloponnesian War. Great wars sometimes begin not because somebody wants a great war but because a sequence of individually rational decisions produces a collectively insane result.

The Nuclear Revolution

There is, however, an enormous difference between Sparta and Athens, or Imperial Germany and Britain, and China and the United States.

Nuclear weapons exist.

This fact is sometimes strangely neglected in discussions of the Thucydides Trap.

Athens could destroy Spartan armies but it could not eliminate Sparta within an afternoon. Britain and Germany could inflict terrible losses upon one another in 1914 but neither possessed weapons capable of destroying the other’s principal cities within minutes.

China and the United States do. That radically alters the logic of great-power competition.

The United States and Soviet Union engaged in an extraordinarily intense strategic confrontation for four decades. They fought proxy wars, armed opposing governments, engaged in espionage, threatened one another and accumulated grotesquely large nuclear arsenals.

Yet they never fought one another directly.

This was not because American and Soviet leaders were invariably wise. They were not. Nor was it because there were no dangerous crises. There were many.

It was because direct war carried the possibility of escalation to mutual destruction.

The same logic applies to China.

This does not make war impossible. Nuclear weapons have never abolished stupidity, accident or miscalculation. But they radically increase the price of deliberate great-power war.

Any American President contemplating direct attacks upon mainland China must consider Chinese nuclear retaliation. Any Chinese leader contemplating attacks upon American bases must consider escalation towards attacks upon the United States itself.

This creates an enormous incentive for restraint.

Economics Matters Too

There is another reason why war is less likely than the simplest version of the Thucydides Trap suggests. China has an enormous amount to lose.

Her extraordinary economic transformation has depended upon international commerce. A major war would threaten maritime trade, foreign investment, access to advanced technology and potentially the stability of China’s own financial system.

The United States would suffer enormously as well.

The idea that America and China can simply “decouple” is politically attractive but economically misleading. Supply chains can be diversified and strategic industries can be relocated. Yet reconstructing decades of integrated production is expensive and slow.

A war would therefore represent not merely a military gamble for Xi Jinping but potentially the destruction of a substantial portion of the economic achievement upon which the Communist Party bases its legitimacy.

The rational Chinese strategy is consequently not necessarily to defeat the United States in war.

It is to become so economically, technologically and militarily powerful that fighting China ceases to be an attractive option.

That distinction is fundamental.

China’s Problem of Time

There is nevertheless a disturbing counterargument.

The conventional Thucydides Trap assumes a rising power. But what happens when the rising power begins to fear that its rise is ending?

China faces serious structural difficulties. Her population is ageing. Her birth rate has fallen dramatically. The property sector has suffered profound problems. Local government indebtedness is substantial. Western countries are restricting Chinese access to certain advanced technologies and increasingly attempting to relocate strategically important supply chains.

China may still become more powerful in absolute terms while becoming less confident about her relative trajectory.

That can be dangerous.

A steadily rising China can afford patience. She can tell herself that time is on her side. A Chinese leadership that believes its window of opportunity is closing may behave differently.

If Beijing concluded that the military balance around Taiwan was favourable today but might become less favourable ten years hence, the temptation to act sooner could theoretically increase.

This is sometimes called the problem of “peaking power”. Historically, states that fear future decline can be at least as dangerous as states enjoying confident ascent.

Hence the greatest danger may not arise when China surpasses the United States. It may arise if Chinese leaders become convinced that China never will.

Donald Trump and Xi Jinping

The relationship between Donald Trump and Xi Jinping adds another unusual dimension.

Trump is instinctively transactional. He is sceptical of some traditional American alliances and often appears more interested in bargains between powerful states than in ideological contests between democracy and authoritarianism.

That creates risks but also opportunities.

A highly ideological American administration might interpret Chinese power itself as something that must ultimately be defeated. Trump is less inclined towards that view. He appears more comfortable with the proposition that China will remain extremely powerful and that the task is therefore to negotiate acceptable terms of coexistence.

The May 2026 Beijing summit was significant for precisely this reason. Its importance lay less in any individual commercial agreement than in the fact that the leaders of the world’s two most powerful countries were talking about how to manage their competition. Recent analysis has similarly argued that US-China competition has become a structural feature of international politics but that competition need not entail armed conflict.

Xi’s invocation of Thucydides was therefore particularly appropriate.

He was effectively saying: we both know what history says might happen next; let us make sure that it does not.

So Will There Be a War?

Probably not.

But “probably not” is not the same thing as “cannot”.

A deliberate Chinese decision to launch a general war against the United States seems highly improbable. A deliberate American decision to attack China is equally difficult to imagine.

Neither country has anything remotely proportionate to gain from such a conflict. The more plausible route to war runs through escalation.

A crisis develops around Taiwan. China announces a blockade. An American naval force attempts to pass through it. Chinese forces fire warning shots. An American vessel is struck. Washington retaliates against the Chinese unit responsible. Beijing attacks an American base. American aircraft attack missile installations on the Chinese mainland.

Within days two governments that never intended to fight one another may discover that they are at war.

This is why military communication, diplomacy and apparently tedious confidence-building measures matter so much.

The objective is not to make America and China friends. They are not going to become friends in any meaningful geopolitical sense. Their interests differ too substantially.

The objective is to ensure that rivalry remains rivalry.

Escaping Thucydides

The Thucydides Trap should ultimately be understood not as a prediction but as a warning.

China is becoming more powerful. The United States remains enormously powerful. Their spheres of strategic concern increasingly overlap. There will therefore be friction.

But friction is not destiny.

Britain peacefully accommodated the rise of the United States during the late nineteenth and early twentieth centuries. The United States and Soviet Union avoided direct war despite decades of hostility. Great-power transitions do not obey mechanical laws.

Indeed there is something dangerous about describing war as inevitable. If Washington believes that China must eventually attack, then every Chinese military development becomes evidence of approaching aggression. If Beijing believes America is determined to prevent China’s rise, every American alliance and export restriction becomes evidence of encirclement.

Both sides then arm themselves against the other’s anticipated hostility.

Each regards its own preparations as defensive and the other’s as aggressive.

Eventually somebody concludes that the war everyone has been preparing for has already effectively begun.

This is precisely the insight contained in Xi Jinping’s 2015 formulation. There may be no Thucydides Trap waiting objectively in the international system. Great powers can nevertheless construct one through repeated strategic miscalculation.

The United States should therefore continue to deter Chinese aggression, particularly against Taiwan, while avoiding the suggestion that America’s ultimate objective is the overthrow of the Chinese state. China should understand that peaceful prosperity is compatible with American power whereas forcible alteration of the regional order may provoke the coalition against China that Beijing most fears.

Taiwan should be made extraordinarily difficult to conquer without being transformed into a platform for threatening mainland China.

The South China Sea requires firm rules, constant communication and restraint by naval commanders who may one day find themselves making decisions upon which millions of lives depend.

Above all, Washington and Beijing must accept an uncomfortable truth. Neither is going away.

China is too large, too rich and too technologically sophisticated to be contained in the manner of the Soviet Union. The United States is too wealthy, too militarily powerful, too geographically secure and too deeply connected with Asian allies to be expelled easily from the western Pacific.

The twenty-first century therefore probably belongs neither to China nor to the United States exclusively.

They will have to share it.

This is frustrating for Washington, which grew accustomed after 1991 to unprecedented international predominance. It is frustrating for Beijing, which increasingly regards American power in Asia as an historical anomaly inherited from an age of Chinese weakness.

Nevertheless coexistence is preferable to the alternative.

A Sino-American war over Taiwan or the South China Sea would not resemble America’s wars in Iraq and Afghanistan. Nor would it resemble Russia’s invasion of Ukraine. It would involve enormous naval and air forces, attacks upon satellites and communications networks, cyber warfare, long-range missiles, disruption of world trade and the constant possibility of nuclear escalation.

Nobody could confidently predict its outcome.

Nobody could confidently control its escalation.

And nobody could plausibly claim that whatever prize initiated the conflict was worth the price.

Thucydides remains worth reading after almost two and a half millennia because he understood that fear can be as powerful a cause of war as ambition. States frequently fight not because they believe themselves strong but because they are frightened of becoming weak.

That is the real danger confronting Washington and Beijing.

China fears encirclement and permanent exclusion from the position in the world that she believes her size and history warrant. The United States fears the erosion of an international order it constructed and the emergence of a Chinese-dominated western Pacific. Each country’s defensive strategy can therefore appear offensive to the other.

The task of statesmanship is to break that circle.

The Thucydides Trap is not a hole in the ground into which America and China are destined to fall. It is something they might build together — decision by decision, military exercise by military exercise, sanction by sanction and misunderstanding by misunderstanding.

Xi Jinping is therefore right about one thing. There is nothing inevitable about it.

And precisely because a Sino-American war would be one of the greatest catastrophes of the twenty-first century, ensuring that it remains avoidable may be the most important responsibility that falls upon the leaders of both countries.