Global Affairs Session 28 4 May 2026

THE THUCYDIDES TRAP

Rising powers, ruling powers and the danger of war

The Thucydides Trap describes the structural danger that emerges when a rising power challenges an established power. Historical transitions show that war is possible but not inevitable: fear, pride, alliances and miscalculation raise the risk, while communication, restraint and workable rules can reduce it.

Core idea Athens versus Sparta America versus China Japan versus the United States How to avoid the trap Glossary

The Thucydides Trap in geopolitics

The Thucydides Trap describes the danger of war when a rising power challenges an established power. The term comes from the ancient Greek historian Thucydides, who argued that the rise of Athens and the fear it created in Sparta made war likely.

• Core idea: Power transitions become dangerous when the growth of a challenger creates fear in the ruling power and confidence in the rising power.
• Modern relevance: The concept is often applied to relations between the United States and China. China’s growing economic, military and technological power creates anxiety in the existing global leader, the United States.
• Not an automatic law: The trap does not mean war is inevitable. It is a warning about risk. Political choices, diplomacy, economic interdependence, crisis management and leadership decisions can reduce the chance of conflict.
• Historical pattern: Some power transitions have led to war, while others have been managed peacefully. The principal dangers are fear, miscalculation, pride, alliance commitments and the belief that postponing action will leave one side weaker later.
• Main lesson: Rising and ruling powers need communication, restraint and clear rules of competition so that strategic rivalry does not become military conflict.

Historical example: Athens versus Sparta

The original historical setting of the Thucydides Trap was the rivalry between a rising Athens and an established Sparta in ancient Greece.

• Rising power: Athens became stronger after the Persian Wars. It built a powerful navy, expanded trade and led the Delian League, which gradually became an Athenian empire.
• Established power: Sparta was the dominant land power in Greece. It feared that Athens’ growing wealth, naval strength and political influence would weaken Sparta’s position.
• Main tension: The conflict was not caused by one event alone. It grew from fear, rivalry, alliance politics and competition for leadership over the Greek world.
• War outcome: The rivalry led to the Peloponnesian War from 431 BCE to 404 BCE. Athens was eventually defeated, but the war weakened much of Greece.
• Lesson: A rising and an established power can fall into war when fear, pride and miscalculation overpower diplomacy and restraint.

America versus China

The contemporary debate centres on whether the United States and China can manage a major shift in power without allowing rivalry to become war.

• Rising power versus ruling power: The United States is the established global power, while China represents the rising power. Graham Allison’s framework argues that such shifts create structural stress because the challenger seeks greater influence while the ruling power fears losing dominance.
• China’s rise challenges United States primacy: China’s economic scale, military modernisation, technological ambition, Belt and Road Initiative and influence in the Indo-Pacific challenge the United States-led international order. This increases rivalry but does not automatically produce war.
• Fear and miscalculation are the real danger: The problem is not only China becoming stronger. American fear of decline and Chinese suspicion of containment can reinforce each other. Taiwan, the South China Sea, cyber conflict, trade restrictions and military incidents could become flashpoints if either side misreads the other’s intentions.
• History warns but does not decide: The historical cases associated with the Thucydides Trap show that conflict has often accompanied power transitions, but peaceful adjustment remains possible.
• Main policy lesson: The central question is not whether strategic rivalry exists, but whether both powers can prevent it from becoming military confrontation.

Japan versus the United States before World War II

The pre-war rivalry between Japan and the United States shows how regional expansion, economic pressure and competing security visions can transform a power transition into military conflict.

• Rising power: Japan emerged as a major industrial and military power in Asia after the Meiji Restoration. Its victories over China in 1895 and Russia in 1905 demonstrated that it could challenge older powers.
• Established power: The United States became a major Pacific power after gaining influence over Hawaii, Guam and the Philippines. It sought to protect trade, naval access and its strategic position in the Pacific.
• Strategic rivalry: Japan sought regional dominance in East Asia, while the United States supported an open Pacific order and opposed Japanese expansion into China and Southeast Asia.
• Escalation: Tensions intensified through Japan’s invasion of Manchuria, the wider war in China, United States sanctions and the oil embargo. Japan viewed these restrictions as threats to its ambitions and security.
• Lesson: Expansion, sanctions, fear and miscalculation can narrow political choices until leaders see war as preferable to compromise.

How to avoid the Thucydides Trap

The trap can be avoided only when both the rising and established powers recognise the risks created by fear, uncertainty and domestic political pressure.

• Accept power shifts realistically: The established power should avoid treating every rise of another country as a threat. The rising power should avoid assuming that growth gives it the right to dominate others.
• Maintain constant communication: Rival powers need direct military, diplomatic and political communication channels. These mechanisms help prevent accidents, misunderstandings and local crises from becoming major wars.
• Create rules for competition: Competition is normal, but it needs limits. Clear understandings on trade, technology, cyber activity, military movement and territorial disputes can reduce dangerous uncertainty.
• Avoid humiliation and aggressive nationalism: Leaders should avoid language or policies that make compromise appear to be weakness. Public pride, historical grievance and nationalist pressure can trap governments into escalation.
• Cooperate where interests overlap: Even rivals can work together on climate change, financial stability, pandemics, nuclear risks, terrorism and AI safety. Limited cooperation can preserve communication and reduce the belief that every issue is a zero-sum contest.

Value addition

Glossary and related terms

Thucydides Trap

The danger of conflict created when a rising power threatens to displace an established power and both sides respond through fear, pressure and strategic rivalry.

Rising power

A state whose economic, military, technological or political capabilities are expanding relative to other major powers.

Ruling power

The established state that holds a leading position in a regional or international order.

Power transition

A shift in the relative strength and influence of major states, especially when a challenger approaches or surpasses the dominant power.

Structural stress

Persistent tension produced by changes in the balance of power, even when neither side initially seeks war.

Miscalculation

An incorrect assessment of another actor’s intentions, capabilities, tolerance or likely response.

Security dilemma

A situation in which one state’s efforts to increase its security make another state feel less secure, prompting countermeasures that leave both worse off.

Strategic rivalry

Long-term competition between states over influence, security, technology, markets, territory or the rules of international order.

Alliance commitment

A formal or informal obligation to support a partner, which can widen a local dispute by drawing additional powers into it.

Crisis management

Communication and decision-making mechanisms designed to prevent a confrontation or accident from escalating into a larger conflict.

Economic interdependence

A condition in which states depend on one another through trade, finance, investment, technology or supply chains.

Rules of competition

Mutually understood boundaries and procedures that permit rivalry while limiting destabilising or escalatory behaviour.

Peloponnesian War

The prolonged war between Athens and Sparta and their respective allies from 431 BCE to 404 BCE.

Containment

A strategy intended to limit the expansion or influence of a rival without necessarily seeking its direct defeat.

Value addition

Conceptual references

• Thucydides’ account of the Peloponnesian War and the relationship between Athens’ rise and Sparta’s fear.
• Graham Allison’s modern formulation of the Thucydides Trap and historical power-transition cases.
• Power-transition theory, the security dilemma and crisis-management concepts in international relations.
• Strategic competition between the United States and China, including technology, trade, maritime security and Indo-Pacific flashpoints.
• The pre-World War II rivalry between Japan and the United States as an example of expansion, sanctions and escalating strategic pressure.