OSD includes the Immediate offices of the Secretary (SECDEF) and the Deputy Secretary of Defense (DEPSECDEF), as well as five Under Secretaries of Defense in the fields of Acquisition, Technology & Logistics; Comptroller/Chief Financial Officer; Intelligence; Personnel & Readiness; and Policy. All of these positions are Presidential appointments which require U.S. Senate confirmation.
Other positions include the Assistant Secretaries of Defense, Assistants to the Secretary of Defense, General Counsel, Director, Operational Test and Evaluation, Director of Administration and Management, and such other staff offices as the Secretary establishes to assist in carrying out their assigned responsibilities.
The Secretary and Deputy Secretary manage several Under Secretaries each of whom in turn manage several Assistant Secretaries of Defense. There are also several special officers reporting directly to Secretary of Defense.
Major elements of OSD (listed hierarchically):
The composition of OSD is in a state of consistent flux, as Congress and DoD routinely create new offices, redesignate existing ones, and abolish others.
During the Obama administration, Congress has sought to clarify the organization of OSD, and has worked with the Department to move toward a standardization of official naming conventions. Many Defense officials, including the Deputy Secretary of Defense (DEPSECDEF), all five Under Secretaries of Defense (USDs), and all Assistant Secretaries of Defense (ASDs), as well as any officials specifically designated in U.S. Code have historically been considered Presidentially-Appointed, Senate-Confirmed (PAS) officials, in that the Senate must provide "advice and consent" for each individual before he or she can operate in an official capacity. In a March 2009 letter, Senator Carl Levin, Chairman of the Senate Armed Service Committee, wrote that the Department was apparently exercising the authority to appoint other significant officials - termed Deputy Under Secretaries of Defense (DUSDs) - "without statutory authorization, without limitation, and without Senate confirmation." Levin was "concerned that the proliferation of DUSDs at multiple levels of the organization could muddy lines of authority and may not be in the best interest of the Department of Defense." Subsequent legislation established five Senate-confirmed Principal Deputies (i.e., "first assistants"), one for each Under Secretary of Defense.
The FY10 NDAA gave the Department of Defense until January 1, 2011, to eliminate or redesignate all other Deputy Under Secretaries who are not Principal Deputy Under Secretaries of Defense (PDUSDs). The FY11 NDAA extended this deadline to January 1, 2015. During that time, the Secretary may, at his or her discretion, appoint within OSD five additional non-PAS DUSDs beyond the five statutory PAS-PDUSDs. The USD(I) appears to be maintaining at least three non-PAS DUSDs, although they have been renamed. The USD (AT&L) has maintained the non-PAS DUSD for Installations and Environment, though the FY11 NDAA recommended merging this post with the newly created ASD for Operational Energy Plans and Programs. The USD(P) has maintained a non-PAS DUSD for Strategy, Plans, and Forces, though the FY11 NDAA recommended eliminating this position.