A growing body of empirical research addresses the influence of domestic political and economic circumstances on the use of force. Most models explain the use of force as a function of various domestic and international demands for military force. This article uses data on U.S. uses of force between 1949 and 1994 to test a model that also considers the influence of these conditions on the supply of this policy instrument. Conditions that have complementary demand and supply effects—making military force both more useful and less costly to employ—are associated with frequent U.S. uses of force in the postwar era. These conditions include high unemployment, strong investor confidence, wartime presidential election years, and the absence of ongoing wars. Some of these same conditions contribute to a motivated bias in international threat perception, leading U.S. decision makers to perceive more opportunities for the use of force when it is most convenient for them to employ it.