This document outlines the roots of U.S. foreign and defense policy since World War 2. It discusses the Cold War era and containment policy, as well as lessons learned from conflicts like Vietnam and the fall of the Soviet Union. Subsequent sections cover major events and security challenges in the post-Cold War period, including the Gulf War, 9/11 attacks, wars in Afghanistan and Iraq, the Arab Spring, and rise of ISIS. It also examines the military dimensions of policy regarding nuclear deterrence, conventional and unconventional warfare, and transnational terrorism. The economic dimensions discussed include trade relations and access to natural resources.