This chapter explores America’s exercise of world power by considering theories of international relations and foreign policy decision-making. Theories are useful in identifying the causes of foreign policy behavior to anticipate, explain, and possibly influence government action. This chapter considers four levels of analysis: the interstate system, civil society, government institutions, and political psychology. Together these levels create a constrained and conflicting environment for policy actors in the U.S. foreign policy process.

This chapter also provides a necessary segue for the next chapters by discussing policy institutions and actors along with how and why policy decisions are made. Specifically, this chapter emphasizes the connection between domestic and international politics, or two-level game pressures on policy makers. These pressures manifest themselves both inside and outside government, making it difficult to achieve a coherent or unitary foreign policy.