10 USC 131 - Office of the Secretary of Defense

(a) There is in the Department of Defense an Office of the Secretary of Defense. The function of the Office is to assist the Secretary of Defense in carrying out his duties and responsibilities and to carry out such other duties as may be prescribed by law.
(b) The Office of the Secretary of Defense is composed of the following:
(1) The Deputy Secretary of Defense.
(2) The Under Secretaries of Defense, as follows:
(A) The Under Secretary of Defense for Acquisition, Technology, and Logistics.
(B) The Under Secretary of Defense for Policy.
(C) The Under Secretary of Defense (Comptroller).
(D) The Under Secretary of Defense for Personnel and Readiness.
(E) The Under Secretary of Defense for Intelligence.
(3) The Deputy Chief Management Officer of the Department of Defense.
(4) The Director of Defense Research and Engineering.
(5) The Assistant Secretaries of Defense.
(6) The Director of Operational Test and Evaluation.
(7) The General Counsel of the Department of Defense.
(8) The Inspector General of the Department of Defense.
(9) Such other offices and officials as may be established by law or the Secretary of Defense may establish or designate in the Office.
(c) Officers of the armed forces may be assigned or detailed to permanent duty in the Office of the Secretary of Defense. However, the Secretary may not establish a military staff in the Office of the Secretary of Defense.
(d) The Secretary of each military department, and the civilian employees and members of the armed forces under the jurisdiction of the Secretary, shall cooperate fully with personnel of the Office of the Secretary of Defense to achieve efficient administration of the Department of Defense and to carry out effectively the authority, direction, and control of the Secretary of Defense.