Read the notes, then try the practice. It adapts as you go.When you're ready.
Session Length
~17 min
Adaptive Checks
15 questions
Transfer Probes
8
International security is the study of threats, policies, and institutions that shape the safety and stability of states and the global order. Rooted in international relations theory, the field examines how nations protect themselves from military aggression, terrorism, cyberattacks, nuclear proliferation, and other transnational dangers. Realist, liberal, and constructivist perspectives each offer distinct explanations for why conflicts arise and how they can be managed, from balance-of-power politics to collective security arrangements and norm-based cooperation.
The scope of international security has expanded considerably since the end of the Cold War. Traditional state-centric concerns such as deterrence, arms control, and alliance management now coexist with non-traditional threats including climate-driven instability, pandemic disease, refugee crises, and information warfare. Organizations like the United Nations Security Council, NATO, and regional bodies attempt to coordinate responses, but disagreements over sovereignty, burden-sharing, and the legitimacy of intervention remain persistent obstacles.
Studying international security equips learners to analyze real-world crises, evaluate defense and foreign-policy decisions, and understand the complex trade-offs between national interest and collective well-being. The field draws on history, political science, economics, law, and technology studies, making it inherently interdisciplinary. Whether assessing nuclear deterrence strategy or debating the ethics of humanitarian intervention, practitioners must weigh evidence, consider multiple stakeholders, and appreciate the uncertainty inherent in global affairs.
One step at a time.
The strategy of discouraging an adversary from taking an unwanted action by threatening a credible and severe response. Deterrence relies on the adversary's rational calculation that the costs of aggression outweigh the benefits.
Example: During the Cold War, the United States and the Soviet Union each maintained thousands of nuclear warheads so that a first strike by either side would guarantee devastating retaliation, a posture known as Mutual Assured Destruction (MAD).
A condition in which no single state or alliance dominates the international system because rival states form coalitions or build up military capability to counterbalance any emerging hegemon.
Example: European states repeatedly formed coalitions against Napoleonic France in the early 19th century to prevent any one power from controlling the continent.
An arrangement in which all member states agree that an attack on one is an attack on all, pledging a unified response to aggression. It aims to replace competitive alliances with a shared commitment to peace.
Example: The United Nations Charter empowers the Security Council to authorize collective military action against an aggressor state, as it did when it sanctioned the coalition to repel Iraq's invasion of Kuwait in 1990.
The spread of nuclear weapons, weapons-usable material, and weapons-applicable technology to states or non-state actors that do not currently possess them. Non-proliferation efforts seek to limit this spread through treaties, inspections, and diplomacy.
Example: The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which entered into force in 1970, commits non-nuclear-weapon states to forgo development of nuclear arms in exchange for access to peaceful nuclear technology and a pledge by nuclear states to pursue disarmament.
A situation in which actions taken by a state to increase its own security, such as building up military forces, cause other states to feel less secure and respond in kind, potentially leading to an arms race or conflict even though neither side intended aggression.
Example: Russia's annexation of Crimea in 2014 prompted neighboring states to increase defense spending and seek closer ties with NATO, which Russia in turn perceived as a threat, deepening mutual distrust.
Terrorism is the use of politically motivated violence against civilians to generate fear and advance ideological goals. Counterterrorism encompasses the strategies, tactics, and institutions designed to prevent, disrupt, and respond to terrorist acts.
Example: After the September 11, 2001 attacks, the United States created the Department of Homeland Security, expanded intelligence-sharing networks, and launched military operations in Afghanistan and Iraq as part of a broad counterterrorism campaign.
The protection of computer networks, data, and critical infrastructure from digital attacks, and the offensive use of cyber capabilities to disrupt, degrade, or destroy an adversary's information systems.
Example: The Stuxnet malware, discovered in 2010, targeted Iranian uranium enrichment centrifuges and is widely attributed to a joint U.S.-Israeli operation, marking one of the first known uses of a cyber weapon to cause physical damage.
The use of military force by external actors in a sovereign state to prevent or halt mass atrocities such as genocide, ethnic cleansing, or crimes against humanity, often justified under the Responsibility to Protect (R2P) doctrine.
Example: NATO's 1999 air campaign against Yugoslavia aimed to stop the ethnic cleansing of Kosovar Albanians, although it was conducted without explicit UN Security Council authorization and sparked debate over the legality and precedent of humanitarian intervention.
More terms are available in the glossary.
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