(a) There is a Deputy Under Secretary of Defense for Personnel and Readiness, appointed from civilian life by the President, by and with the advice and consent of the Senate.

(b) The Deputy Under Secretary of Defense for Personnel and Readiness shall assist the Under Secretary of Defense for Personnel and Readiness in the performance of the duties of that position. The Deputy Under Secretary of Defense for Personnel and Readiness shall act for, and exercise the powers of, the Under Secretary when the Under Secretary is absent or disabled.