The Under Secretary of Defense for Acquisition & Sustainment (USD(A&S)) is the principal staff assistant and advisor to the Secretary of Defense and the Deputy Secretary of Defense for all matters concerning Departmental acquisition and sustainment.

ASD(R&E) provides science and technology leadership throughout the Department of Defense to meet tomorrow's challenges

Secretary of Defense for Special Operations/Low-Intensity Conflict (ASD/SOLIC) is the principal civilian advisor to the Secretary of Defense on special operations and low-intensity conflict matters. The ASD (SO/LIC) has as his principal duty overall supervision (to include oversight of policy and resources) of special operations and low-intensity conflict activities. These core tasks, according to USSOCOM's 2007 Posture Statement, include counter-terrorism; unconventional warfare; direct action; special reconnaissance; foreign internal defense; civil affairs, information and psychological operations; and counter-proliferation of WMD. Section 167 of Title 10 USC provides a very similar but not identical list of SOF activities.

The Goldwater-Nichols DOD Reorganization Act of 1986 identifies the Chairman of the Joint Chiefs of Staff as the senior ranking member of the Armed Forces. As such, the Chairman of the Joint Chiefs of Staff is the principal military adviser to the President. He may seek the advice of and consult with the other JCS members and combatant commanders. When he presents his advice, he presents the range of advice and opinions he has received, along with any individual comments of the other JCS members.

As Secretary of the Army, this position has statutory responsibility for all matters relating to the United States Army: manpower, personnel, reserve affairs, installations, environmental issues, weapons systems and equipment acquisition, communications, and financial management.

The Commandant of the Marine Corps (CMC) is normally the highest-ranking officer in the United States Marine Corps and is a member of the Joint Chiefs of Staff.  The CMC reports directly to the United States Secretary of the Navy and is responsible for ensuring the organization, policy, plans, and programs for the Marine Corps as well as advising the President, the Secretary of Defense, the National Security Council, the Homeland Security Council, and the Secretary of the Navy on matters involving the Marine Corps. Under the authority of the Secretary of the Navy, the CMC designates Marine personnel and resources to the commanders of Unified Combatant Commands. The Commandant performs all other functions prescribed in Section 5043 in Title 10 of the United States Code or delegates those duties and responsibilities to other officers in his administration in his name. As with the other joint chiefs, the Commandant is an administrative position and has no operational command authority over United States Marine Corps forces.

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The Commandant is nominated by the President for a four-year term of office and must be confirmed by the Senate. By statute, the Commandant is appointed as a four-star general while serving in office. The Commandant is directly responsible to the Secretary of the Navy for the total performance of the Marine Corps. This includes the administration, discipline, internal organization, training, requirements, efficiency, and readiness of the service. The Commandant is also responsible for the operation of the Marine Corps material support system.

The Secretary of the Navy (SECNAV) is responsible for, and has the authority under Title 10 of the United States Code, to conduct all the affairs of the Department of the Navy, including: recruiting, organizing, supplying, equipping, training, mobilizing, and demobilizing. The Secretary also oversees the construction, outfitting, and repair of naval ships, equipment and facilities.

SECNAV is responsible for the formulation and implementation of policies and programs that are consistent with the national security policies and objectives established by the President and the Secretary of Defense. The Department of the Navy consists of two uniformed Services: the United States Navy and the United States Marine Corps.

The Secretary of the Air Force (SecAF, or SAF/OS) is the head of the Department of the Air Force, a component organization within the Department of Defense of the United States. The Secretary of the Air Force is appointed from civilian life by the President, by and with the advise and consent of the Senate. The Secretary reports to the Secretary of Defense and/or the Deputy Secretary of Defense, and is by statute responsible for and has the authority to conduct all the affairs of the Department of the Air Force.