Table of Contents

What Is International Relations?

International relations (IR) is the study of how countries, international organizations, corporations, and other actors interact on the global stage. It covers diplomacy, war, trade, alliances, human rights, environmental agreements, migration, and everything else that happens between states — or that requires cooperation across borders to address.

Why Countries Do What They Do

The central question of IR is simple: why do states behave the way they do? The answers depend on which theoretical framework you find most persuasive.

Realism — the oldest and most influential perspective — argues that international politics is fundamentally about power. There is no world government (the system is “anarchic”), so each state must ensure its own survival. States build militaries, form alliances, and compete for influence because nobody else will protect them. Realists predict that great powers will always compete, cooperation is fragile, and international institutions only work when powerful states find them useful.

Liberalism offers a more optimistic view. International institutions (the UN, WTO, NATO), economic interdependence (trade), and democratic governance can create frameworks for cooperation that benefit everyone. Trade makes war expensive. Institutions provide forums for resolving disputes. Democracies rarely fight each other (the “democratic peace” theory). Liberals acknowledge that the system is anarchic but argue that anarchy can be managed.

Constructivism focuses on ideas, norms, and identities. The Cold War ended not because of military defeat but because Soviet leaders changed their beliefs about their system. Human rights norms spread because activists and organizations changed expectations about how states should treat their citizens. International politics is not fixed by material factors — it is constructed by the ideas people hold.

The Major Institutions

The United Nations (founded 1945) — 193 member states. The General Assembly gives every country one vote. The Security Council has 15 members, including five permanent members (U.S., UK, France, Russia, China) with veto power. The veto makes the Council effective when the permanent members agree and paralyzed when they don’t.

NATO (1949) — a military alliance of 32 countries committed to collective defense. An attack on one member is treated as an attack on all. Originally created to counter the Soviet Union, NATO expanded after the Cold War to include former Warsaw Pact countries — a decision that remains bitterly controversial.

The World Trade Organization (1995) — sets rules for international trade and resolves trade disputes. It oversees roughly 98% of world trade and operates by consensus, which makes negotiations slow but outcomes broadly accepted.

The European Union — the most ambitious international organization in history. Twenty-seven countries share a common market, a common currency (for 20 of them), and supranational institutions that make binding law. It demonstrates both the possibilities and difficulties of deep international cooperation.

Great-Power Competition

The structure of international politics is shaped by the distribution of power among major states. Since 1945, this has evolved through three phases:

Bipolarity (1947-1991) — the U.S. and Soviet Union dominated global politics. The Cold War was “cold” between them (no direct military conflict) but hot through proxy wars in Korea, Vietnam, Afghanistan, and elsewhere. Nuclear deterrence — the doctrine of mutual assured destruction (MAD) — prevented direct confrontation.

Unipolarity (1991-2010s) — after the Soviet collapse, the U.S. was the sole superpower. This period saw NATO expansion, the spread of liberal democracy, and U.S. military interventions (Gulf War, Kosovo, Afghanistan, Iraq). Some viewed American dominance as stabilizing; others viewed it as imperial overreach.

Emerging multipolarity (2010s-present) — China’s rise, Russia’s reassertion, and the relative decline of American dominance are reshaping global politics. The U.S. remains the most powerful single state, but the gap is narrowing. Whether this transition produces managed competition or dangerous conflict is the central question of contemporary IR.

Non-State Actors

States are not the only players. International politics increasingly involves:

International organizations — the UN, WTO, IMF, WHO, and hundreds of others shape rules, norms, and responses to global challenges.

Multinational corporations — Apple, Shell, Nestle, and other global companies have revenues exceeding the GDP of many countries. Their investment decisions, supply chains, and lobbying efforts influence state behavior.

NGOs — organizations like Amnesty International, Greenpeace, and Doctors Without Borders advocate for human rights, environmental protection, and humanitarian action. They shape public opinion and hold governments accountable.

Terrorist and criminal networks — operate across borders and challenge state authority in ways traditional IR theories struggle to explain.

Contemporary Challenges

Climate change is the ultimate collective action problem. Every country benefits from emissions reductions but has incentives to let others bear the cost. The Paris Agreement (2015) represents progress but remains insufficient — current commitments leave the world on track for 2.5-3 degrees Celsius of warming.

Nuclear proliferation — nine countries possess nuclear weapons. Preventing additional states (and non-state actors) from acquiring them is an ongoing challenge.

Migration — over 100 million people are forcibly displaced worldwide. Managing migration flows while respecting human rights strains international cooperation.

Technology competition — artificial intelligence, quantum computing, and biotechnology are becoming arenas of great-power competition with implications for military capability, economic power, and social control.

The world is more interconnected than ever before, yet the tools for managing that interconnection remain underdeveloped. How to govern a globalized world without a global government is the defining challenge of international relations.

Frequently Asked Questions

What are the main theories of international relations?

The three dominant theories are realism (states pursue power and security in an anarchic system), liberalism (international institutions, trade, and democracy can promote cooperation), and constructivism (international politics is shaped by shared ideas, norms, and identities). Each offers a different lens for explaining why states behave as they do.

What does the UN actually do?

The United Nations provides a forum for diplomacy, coordinates international responses to crises, deploys peacekeeping forces (currently about 87,000 personnel in 12 missions), sets international standards (human rights, trade, environment), and delivers humanitarian aid. It cannot compel states to act — the Security Council's five permanent members can veto any binding resolution.

Is the world becoming more peaceful?

The long-term trend is positive. Interstate wars have declined dramatically since 1945. Deaths from conflict per capita are at historic lows. But civil wars, terrorism, and hybrid warfare persist. Nuclear weapons remain an existential threat. And the post-Cold War international order is under increasing strain from great-power competition, authoritarianism, and transnational challenges like climate change.

Further Reading

• Council on Foreign Relations
• UN Charter
• Foreign Affairs Magazine