The American Military in the Twenty-First Century assesses the likely roles of U.S. military forces in the changed international environment of the twenty-first century and how military roles and missions might best be allocated among the armed services to create a flexible, cost-effective force able to support U.S. national interests. It focuses on the basic functions of the armed forces (for example, defence of the homeland, projection of power abroad, and peacekeeping and humanitarian operations) and shows, with an illustrative force posture, how military capabilities might best be adjusted to meet the country's defence and foreign policy needs in the decades ahead.