The United States Armed Forces are the military forces of the United States of America. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard. The U.S. has a strong tradition of civilian control of the military. The President is the military's overall head, and helps form military policy with the U.S. Department of Defense (DoD), a federal executive department, acting as the principal organ by which military policy is carried out. The DoD is headed by the Secretary of Defense, who is a civilian and Cabinet member. The Defense Secretary is second in the military's chain of command, just below the President, and serves as the principal assistant to the President in all DoD-related matters.