Balance of Power

The balance of power is perhaps the most enduring concept in the study of international relations. At its core, it holds that states will act to prevent any single power from achieving dominance—because a hegemon, unchecked, could threaten the independence of all others. The principle is simultaneously descriptive (explaining how states behave) and prescriptive (advising how statesmen should act).

This principle has guided statecraft for over four centuries, from the Peace of Westphalia in 1648 to the Cold War to contemporary debates about the rise of China. Every major war in modern history can be understood, at least in part, as either a challenge to the existing balance or an attempt to restore it.

The Basic Logic¶

The balance of power rests on several foundational assumptions about how the international system operates:

States seek survival: Above all else, states want to preserve their independence and territorial integrity. This is the foundational assumption of realism in international relations theory. A state that loses its independence—absorbed by conquest, reduced to satellite status, or dismembered—ceases to be a meaningful actor. Everything else (economic prosperity, ideological goals, domestic welfare) depends on the state’s continued existence.

Anarchy defines the system: Unlike domestic politics, where a government holds a monopoly on legitimate force, the international system has no overarching authority. States exist in what theorists call “anarchy”—not chaos, but the absence of a world government. In this environment, each state must ultimately rely on itself for security.

Power is relative: A state’s security depends not only on its own capabilities but on how those capabilities compare to potential adversaries. An army of 100,000 is strong or weak depending on what the neighbors can muster. France felt secure with an army of 500,000 in 1913—until Germany mobilized 3.8 million men. China’s 2-million-strong military appears formidable until one considers American technological advantages.

Concentrated power threatens others: A state powerful enough to dominate the system has the capability to threaten others, even if it lacks the immediate intention. Prudent statesmen do not bet national survival on the goodwill of the powerful. Intentions can change overnight—with a new leader, a new ideology, a new grievance—but the capability to threaten persists. As the Greek historian Thucydides observed 2,400 years ago, states fear not what others intend but what they might do.

Balancing is the natural response: When one state grows too strong, others will combine against it—either by building up their own power (internal balancing) or by forming alliances (external balancing). This is not necessarily a conscious choice but rather a structural imperative: states that fail to balance against rising threats tend to be conquered or subordinated, while those that balance survive.

The result, in theory, is an equilibrium: no state achieves dominance, and the system persists in a condition of competitive coexistence. Wars may occur, but they tend to be limited rather than hegemonic, and the system of independent states endures.

Historical Practice¶

The European System¶

The classic laboratory for balance-of-power politics was early modern Europe. After the Peace of Westphalia (1648) ended the Thirty Years’ War, the continent settled into a system of sovereign states with no overarching authority. The Holy Roman Empire was revealed as a hollow shell; the Catholic Church had lost its claim to temporal supremacy; and the major powers—France, Britain, Austria, Prussia, Russia—engaged in constant competition for territory, trade, and prestige.

The Wars of Louis XIV (1667-1714): France under Louis XIV made the first serious bid for European hegemony. With a population of 20 million (twice that of Spain, three times that of England), the largest army in Europe (400,000 men at its peak), and the most sophisticated state apparatus, France seemed poised to dominate. The response was a classic balancing coalition: the Grand Alliance united Britain, the Dutch Republic, Austria, and eventually most of Europe against French expansion. Four major wars over half a century exhausted France and preserved the balance.

Britain as the balancer: For centuries, Britain pursued a deliberate balance-of-power strategy articulated in the maxim “no permanent friends, no permanent enemies, only permanent interests.” As an island nation protected by the English Channel and the Royal Navy, it had the luxury of choosing when and how to intervene on the continent. British policy consistently opposed whichever power threatened to dominate: Spain under Philip II, France under Louis XIV and Napoleon, Germany under the Kaiser and Hitler. Britain spent approximately 75% of its military effort in coalition warfare over three centuries, almost always on the weaker side against the stronger.

The Concert of Europe (1815-1914): After Napoleon’s defeat at Waterloo, the great powers established the Concert of Europe—a loose arrangement for managing conflicts and preventing any state from again bidding for hegemony. The Congress of Vienna (1815) restored the balance, and subsequent congresses addressed crises that might upset it. The system preserved relative peace for a century—no great power war occurred between 1815 and 1914, a remarkable achievement in European history. Yet the Concert ultimately failed: the rise of Germany, unified in 1871 and possessing by 1914 the largest economy and army in Europe, triggered the balancing dynamics that led to World War I.

The Failure of 1939¶

The interwar period (1919-1939) represents perhaps the most consequential failure of balance-of-power politics in modern history. Germany, though defeated in 1918, retained the industrial capacity and population (65 million) to again bid for hegemony. The Treaty of Versailles sought to restrain Germany through territorial losses, military limits (100,000 soldiers, no air force, no tanks), and reparations of 132 billion gold marks.

Yet balancing failed catastrophically. Britain and France, exhausted by World War I (which cost them 1.7 million dead combined), proved unwilling to enforce the Versailles settlement. The United States retreated into isolationism. The Soviet Union was excluded from the European system. When Hitler began rearming in 1933, remilitarizing the Rhineland in 1936, annexing Austria in 1938, and seizing Czechoslovakia in 1938-39, the democracies responded with appeasement rather than balancing.

Only when Germany invaded Poland in September 1939 did Britain and France finally declare war—by which point the Wehrmacht had grown to 3.7 million men and Germany had absorbed territories containing 10 million additional Germans. The balance had shifted decisively; restoring it required six years of total war and 70 million dead.

The Cold War¶

The bipolar structure of the Cold War (1947-1991) represented balance of power in its starkest form. The united-states and Soviet Union divided the world into spheres of influence, each deterring the other with nuclear weapons and alliance networks. For 44 years, the two superpowers managed their competition without direct military confrontation—a remarkable achievement given the intensity of their rivalry.

The balance was maintained by several interlocking mechanisms:

Nuclear deterrence: By the 1960s, both sides possessed thousands of nuclear weapons capable of destroying civilization. The doctrine of Mutual Assured Destruction (MAD) meant that neither side could attack the other without ensuring its own annihilation. The Soviet arsenal peaked at approximately 40,000 warheads; the American at 31,000.
Alliance systems: NATO (established 1949) aggregated the industrial and military power of North America and Western Europe—by 1989, approximately 57% of global GDP. The Warsaw Pact (1955) unified Eastern Europe under Soviet command. Each alliance committed members to collective defense, multiplying the effective power of the leading state.
Proxy competition: Rather than direct confrontation, the superpowers competed through allies and client states. The Korean War (1950-53, approximately 5 million dead), Vietnam War (1955-75, approximately 3 million dead), and dozens of smaller conflicts in Africa, Latin America, and Asia allowed the superpowers to test each other without risking nuclear escalation.
Arms control: Beginning with the Limited Test Ban Treaty (1963) and continuing through SALT I (1972), SALT II (1979), and START (1991), the superpowers negotiated limits on their nuclear arsenals. These agreements did not eliminate the competition but channeled it into predictable forms.

The Cold War balance ultimately shifted against the Soviet Union. By 1991, the USSR’s GDP had fallen to approximately $2.7 trillion versus America’s $6.2 trillion. Soviet defense spending consumed perhaps 25% of GDP (compared to 6% for the United States), an unsustainable burden. The balance held until economic exhaustion forced one side to concede.

Varieties of Balance¶

Political scientists and historians distinguish several forms of balance-of-power systems:

Bipolar balance: Two powers of roughly equal strength check each other, as in the Cold War. Bipolar systems tend to be stable because the lines are clear, miscalculation is difficult, and each side can focus its attention on a single rival. However, they can be dangerous because any shift in the balance directly threatens the other power.

Multipolar balance: Multiple great powers of varying strength form shifting coalitions, as in 18th-century Europe. The classic multipolar system featured five great powers (Britain, France, Austria, Prussia, Russia) that aligned and realigned depending on circumstances. Multipolar systems offer flexibility—today’s enemy may be tomorrow’s ally—but are prone to miscalculation because commitments are uncertain and the balance is harder to assess.

Regional balance: Equilibrium at the regional level, with external powers sometimes intervening to preserve it. The middle-east today features a balance between israel, Iran, Saudi Arabia, and Turkey, with the united-states acting as an external balancer. South Asia has long featured an Indo-Pakistani balance, with china tilting toward Pakistan. Regional balances can be disrupted by nuclear proliferation, internal collapse, or shifts in external support.

Offshore balancing: A powerful maritime state remains aloof from regional competition, intervening only when a potential hegemon emerges. Britain practiced this strategy for centuries, committing troops to the continent only when France or Germany threatened to dominate. Some American strategists, including john-mearsheimer, advocate offshore balancing as the optimal strategy for the United States—maintaining dominance in the Western Hemisphere while allowing regional powers in Europe and Asia to balance against local threats, intervening only when the balance fails.

Hegemonic stability: Some theorists argue that balance of power is not the natural state of international relations. Instead, a single dominant power—a hegemon—may provide order that benefits most states. The British-led system of the 19th century and the American-led system after 1945 offered public goods (free trade, freedom of navigation, a stable currency) that other states valued. In this view, the balance of power is what emerges when hegemony fails, not the optimal arrangement.

Mechanisms of Balancing¶

Internal Balancing¶

States can build up their own capabilities to match or exceed potential threats:

Expanding military forces: Germany increased its army from 100,000 (the Versailles limit) to 3.7 million by 1939; China has expanded its navy from 50 major surface combatants in 1990 to over 350 today
Developing new weapons technologies: The Manhattan Project, which cost $2 billion (approximately $30 billion in 2024 dollars) and employed 125,000 people, was America’s internal balancing response to the threat of Nazi nuclear weapons
Strengthening economic foundations of power: Japan’s Meiji Restoration (1868) explicitly aimed at building the economic base for military power; China’s economic reforms after 1978 have a similar strategic logic
Mobilizing population for war: Total mobilization in World War II saw the Soviet Union field 34 million soldiers over the course of the war, the United States 16 million

Internal balancing is slow but reliable—a state controls its own resources and does not depend on the uncertain commitments of allies. It also signals resolve: a state that invests heavily in military capability demonstrates that it takes threats seriously.

External Balancing¶

States can aggregate power through alliances:

Formal defense pacts: NATO’s Article 5 commits all members to treat an attack on one as an attack on all; similar guarantees bind the United States to Japan, South Korea, Australia, and the Philippines
Extending security guarantees: The American “nuclear umbrella” extends deterrence to allies who forgo their own nuclear weapons
Coordinating military planning: NATO maintains integrated command structures and standardized equipment; the Quad (US, Japan, India, Australia) conducts joint naval exercises
Pooling economic resources: sanctions regimes aggregate economic pressure; the Western response to Russia’s 2022 invasion of Ukraine coordinated sanctions across the G7 and EU

External balancing is faster than internal buildup but carries risks. Allies may defect (Italy switched sides in both World Wars), free-ride (NATO allies consistently underspend on defense relative to their commitments), or drag each other into unwanted conflicts (Austria’s ultimatum to Serbia in 1914 triggered German and then Russian mobilization). The credibility of alliance commitments is always in question.

Bandwagoning: The Alternative¶

Not all states balance against rising powers. Some bandwagon—they align with the stronger side rather than against it.

Bandwagoning may occur when:

A state is too weak to balance effectively: Small states near great powers often have no choice but to accommodate (Finland’s “Finlandization” during the Cold War)
Ideological affinity favors alignment: Communist parties worldwide aligned with Moscow; authoritarian states today may feel more comfortable with Beijing than Washington
Geographic exposure makes resistance futile: Eastern European states could not resist Soviet domination; Central Asian states today must balance carefully between russia and china
The rising power offers inducements: China’s Belt and Road Initiative has brought dozens of states into closer economic relationships

The debate between balancing and bandwagoning is central to contemporary analysis of how states respond to China’s rise. Stephen Walt’s “balance of threat” theory refines the analysis by arguing that states balance not against power alone but against threats—which depend on power, geographic proximity, offensive capability, and perceived aggressive intentions.

Criticisms of Balance of Power¶

Theoretical Problems¶

Ambiguity: What exactly must be balanced? Military power? Economic capacity? Some overall index of “national power”? The concept is notoriously imprecise.

When does balancing occur?: States often delay balancing until threats become acute—by which time it may be too late. Nazi Germany was allowed to grow powerful before effective resistance formed.

Domestic politics matters: The balance-of-power framework assumes states respond rationally to external threats. In practice, domestic ideologies, regime interests, and leadership psychology shape foreign policy.

Empirical Problems¶

Balancing failure: History is littered with cases where balancing failed or never occurred:

The Greek city-states failed to unite against Macedon
The Italian states failed to balance against France in the 16th century
Interwar Europe failed to balance effectively against Germany until 1939

Unipolarity: After the Cold War, the United States enjoyed unprecedented dominance. Balance-of-power theory predicted that other states would combine against American hegemony. Decades later, no effective counterbalancing coalition has emerged—though some argue this is now changing.

Contemporary Applications¶

The Rise of China¶

The most consequential balance-of-power question today concerns China’s ascent. China’s GDP has grown from $360 billion in 1990 to over $17 trillion today (or approximately $30 trillion in purchasing power parity terms), transforming it from a regional power into a potential peer competitor to the United States. Its military budget, officially $225 billion in 2023 (though likely higher), is now second only to America’s $886 billion.

The key questions for balance-of-power analysis:

Will regional powers balance against Beijing? Japan has increased defense spending to approximately 2% of GDP and loosened restrictions on military operations. India has strengthened ties with the United States through the quad. Vietnam and the Philippines have pushed back against Chinese claims in the south-china-sea. Australia has joined aukus and acquired nuclear-powered submarines. Yet none has fully committed to containing China.
Will the United States sustain its Asian commitments? American strategy since the “pivot to Asia” under Obama has emphasized the Indo-Pacific, but domestic politics and competing priorities (Russia, the Middle East) create uncertainty. The US maintains 80,000 troops in the Indo-Pacific and mutual defense treaties with Japan, South Korea, the Philippines, Australia, and Thailand.
Will China’s neighbors bandwagon rather than resist? Economic interdependence complicates balancing: China is the largest trading partner of Japan, South Korea, and most of Southeast Asia. States may prefer accommodation to confrontation.
Can competition remain stable? The thucydides-trap framework suggests that rising powers and established powers are prone to war. Yet nuclear weapons, economic interdependence, and institutional constraints may preserve peace despite rivalry.

Different answers to these questions yield radically different expectations about the 21st century.

The Russia Question¶

Russia’s invasion of Ukraine in February 2022 triggered a classical balancing response that surprised many observers—including, apparently, the Kremlin:

NATO expanded to include Finland (2023) and Sweden (2024), adding 1,300 kilometers to NATO’s border with Russia and two capable militaries (Finland maintains 280,000 trained reserves; Sweden has an advanced defense industry)
European states increased defense spending: Germany announced a €100 billion special defense fund and committed to 2% of GDP; Poland moved toward 4% of GDP
Unprecedented sanctions aggregated economic pressure against Moscow, freezing approximately $300 billion in Russian central bank reserves and cutting Russia off from Western financial systems
Military aid to Ukraine exceeded $100 billion by 2024, including advanced weapons (HIMARS, Patriot missiles, Leopard tanks) that transformed Ukrainian combat capability

Whether this balancing is sufficient—and sustainable—remains unclear. Russia retains significant military capacity and nuclear weapons. European unity may fray as costs mount. The United States may shift focus to China. The balance in Eastern Europe remains contested.

Multipolarity and the Future¶

Many analysts argue the world is transitioning from American unipolarity (which prevailed from 1991 to approximately 2010) to a multipolar system featuring the US, China, and perhaps the EU, Russia, and india as major poles. If so, balance-of-power dynamics will likely intensify:

Shifting alignments: The Sino-Russian partnership, while not a formal alliance, represents a significant combination of capabilities directed against American influence. India, despite quad membership, maintains strategic autonomy and purchases Russian arms. Middle Eastern states balance between Washington and Beijing.
Regional balances: Multiple regional balance-of-power systems may operate simultaneously—in Europe (NATO vs. Russia), Asia (US-led coalition vs. China), and the Middle East (israel and Gulf states vs. Iran)—with uncertain connections between them.
Increased competition: Multipolar systems historically produce more frequent wars than bipolar systems, though none involving great powers directly since 1945. The question is whether nuclear weapons and economic interdependence have fundamentally changed the dynamics.

The Moral Dimension¶

Balance-of-power politics has always attracted criticism on ethical grounds:

Amorality: It treats states as amoral units seeking only power and survival, ignoring the ideological and normative differences between democratic and authoritarian regimes. During World War II, the United States and Britain allied with Stalin’s Soviet Union—responsible for millions of deaths through purges and engineered famines—because the balance required it.
Unsavory alliances: It justifies alliances with dictatorships, human rights violators, and corrupt regimes if they serve the balance. American support for Saudi Arabia, despite its repression of dissent and conduct in Yemen, follows balance-of-power logic (containing Iran). Critics argue this undermines American values and credibility.
Perpetuating conflict: It may perpetuate conflict by assuming competition is inevitable. If states believe that power is the only currency of international relations, they may ignore opportunities for cooperation and institution-building that could mitigate the security dilemma.
Self-fulfilling prophecy: States that assume others are threats may provoke the very hostility they fear. NATO expansion, whatever its merits, may have contributed to Russian threat perception and the very aggression it sought to deter—a classic security dilemma.

Defenders argue that the balance of power, for all its flaws, has prevented the worst outcome: universal empire under a single dominating power. The Roman Empire, the Mongol conquests, Nazi Germany’s bid for European hegemony—history suggests that unchecked power tends toward tyranny. The competitive state system, with all its wars and rivalries, has also enabled diversity, liberty, and progress in ways a world empire might not.

Moreover, defenders note that alternatives to balance-of-power thinking have not fared well. The League of Nations, founded on the premise that collective security could replace balance-of-power politics, collapsed in the 1930s. International law and institutions, while valuable, depend ultimately on power to enforce them. Until human nature changes or world government arrives, states must attend to the balance.

Conclusion¶

The balance of power is not a law of nature. States do not automatically balance against rising powers, and when they do, they often do so too late or ineffectively. The Greek city-states failed to balance against Macedon; the Italian states failed against France; interwar Europe failed against Germany. The concept is better understood as a recurring pattern and a strategic framework than as an iron law.

Yet the logic of the balance endures because its foundational premise endures: in a world without a global sovereign, states must look to their own security, and concentrated power is inherently threatening to those who do not possess it. This was true in ancient Greece, in Renaissance Italy, in 18th-century Europe, and during the Cold War. There is no reason to believe the 21st century will be different.

Understanding balance-of-power thinking is essential for interpreting contemporary geopolitics—the rise of China, the Russian challenge to European security, the shifting alignments of the Middle East. It is equally essential for recognizing the concept’s limitations: the role of domestic politics, the importance of perception and ideology, the possibility that institutions and interdependence may modify (though not abolish) the relentless logic of power competition.

The balance of power will not tell you everything about international relations. But no serious analysis of world politics can proceed without it.

Sources & Further Reading¶

The Origins of Alliances by Stephen M. Walt — The definitive modern treatment of how and why states balance against threats, introducing “balance of threat” theory as a refinement of classical balance of power.
Theory of International Politics by Kenneth N. Waltz — The foundational text of structural realism, explaining how the anarchic international system generates balancing behavior among states.
The Tragedy of Great Power Politics by John J. Mearsheimer — Argues that great powers are compelled to seek hegemony and that balancing is the inevitable response, with implications for US-China competition.
Europe’s Last Summer: Who Started the Great War in 1914? by David Fromkin — A detailed examination of how balance-of-power calculations failed catastrophically, leading to World War I.
After Hegemony by Robert O. Keohane — Challenges pure balance-of-power theory by showing how institutions can facilitate cooperation even as power shifts.