10 U.S.C. § 137a — Deputy Under Secretaries of Defense

(a) There are exactly six Deputy Under Secretaries of Defense. (1) That's the total number allowed. (2) The President appoints them from civilian life, and the Senate must approve. (3) These six positions are the only ones allowed to carry the title Deputy Under Secretary of Defense. (b) Each Deputy Under Secretary is the "first assistant" to one Under Secretary of Defense. That means each one helps that Under Secretary do the job, and steps in to act for that Under Secretary — using that Under Secretary's powers — if the Under Secretary dies, resigns, or otherwise can't do the job. (c) The six Deputy Under Secretary positions are: (1) Deputy Under Secretary of Defense for Research and Engineering. (2) Deputy Under Secretary of Defense for Acquisition and Sustainment. (3) Deputy Under Secretary of Defense for Policy. (4) Deputy Under Secretary of Defense for Personnel and Readiness. (5) Deputy Under Secretary of Defense (Comptroller). (6) Deputy Under Secretary of Defense for Intelligence and Security — this one must be chosen from people with deep expertise in intelligence matters. (d) In line of precedence within the Department of Defense, the Deputy Under Secretaries rank after the Secretary of Defense, the Deputy Secretary of Defense, the Secretaries of the military departments, and the Under Secretaries of Defense. Among themselves, they rank in whatever order the Secretary of Defense sets.