A key concept and problem in international relations, the security dilemma obtains when one state's attempts to increase its security decreases the security of other states. The security dilemma's consequences are said to include unnecessary armament and conflict spirals. Described herein is an in-class exercise that challenges students to role-play government decision-makers in a stylized international system of states with no explicit revisionist aims, nor incentives for aggression. Decisionmakers must choose how to allocate resources between "guns" and "butter", which seems a straightforward decision problem until uncertainty is amplified by defecting spies, who share information about neighboring states' armament plans. The ensuing dynamics typically include arms racing and conflict spirals, thus illustrating the operation of the security dilemma, and providing the class with an opportunity to experience firsthand an emergent security dilemma, and to discuss its operation and implications for world politics.