Defense, Secretary of

Since the end of the Second World War, the president appoints one person—a civilian retired from military service for at least 7 years—to advise the president on matters of national security and to direct the Department of Defense. Sitting on the president’s cabinet and National Security Council, the secretary of defense is a position of immense national influence and international significance. This entry describes the responsibilities of the secretary of defense, examines influential secretaries of defense in U.S. history, and concludes with an assessment of the position’s challenges in the 21st century.