The Department of Defense (DOD) is a federal executive department responsible for providing the military forces needed to deter war and protect the security of the United States. The DOD is composed of three parts: the Office of the Secretary of Defense, the Joint Chiefs of Staff, and the Military Departments. The Office of the Secretary of Defense is responsible for the overall management of the DOD, while the Joint Chiefs of Staff provide advice and assistance to the President and the Secretary of Defense on military matters. The Military Departments are responsible for the organization, training, and equipping of the armed forces.