Preventive war

A preventive war is launched to stop a possible future threat from growing more dangerous, rather than to meet an imminent attack.

Preemptive war: A war launched to forestall an attack judged imminent. Unlike preventive war, it responds to an immediate threat rather than a danger that may grow later.
Power transition theory: A theory that major-war risk rises when a rising power approaches the dominant state's capabilities. It explains why leaders may fear waiting as a rival gains strength.
Six-Day War: The June 1967 war in which Israel fought Egypt, Jordan, and Syria. Debate over whether Israel faced an imminent attack or acted preventively illustrates the boundary with preemption.
United Nations Charter: The 1945 treaty establishing the United Nations and setting rules for international relations. Its prohibition on force, with exceptions for self-defense and Security Council authorization, frames preventive-war legality.
Preventive diplomacy: Diplomatic action intended to prevent disputes from escalating into armed conflict. It pursues prevention through negotiation and policy rather than war.
Security dilemma: A dynamic in which one state's defensive measures make other states feel less secure. Mutual threat perceptions can make preventive motives appear defensive on both sides.
Iraq War: The 2003 invasion of Iraq led by a United States–led coalition. Its advocates invoked future danger from Iraq's alleged weapons programs; those claims were later discredited.
Anticipatory self-defense: The contested claim that a state may use force before an armed attack occurs. Its disputed legal limits determine whether some preventive action can qualify as self-defense.
Deterrence: A strategy that discourages an adversary from acting by threatening unacceptable costs. Deterrence seeks to contain a future threat without initiating war.
Commitment problem: A bargaining problem in which actors cannot credibly promise to honor future agreements. A state may attack if it expects a stronger rival to break agreements later.

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