; (iii) serve as the Staff Director of the Nuclear Weapons Council established by section 179 of this title; (iv) serve as the principal interface with the Department of Energy on issues relating to nuclear fuels, and in coordination with the Assistant Secretary of Defense for Energy, Installations, and Environment, advise the Secretary of Defense on nuclear energy matters; and (v) advise the Secretary of Defense, the Under Secretary of Defense for Acquisition and Sustainment, and the Under Secretary of Defense for Policy on all matters relating to defending against chemical, biological, and other weapons of mass destruction. (B) In the discharge of the responsibilities specified in subparagraph (A), the Assistant Secretary is immediately subordinate to the Secretary of Defense. Unless otherwise directed by the President or statute, no officer other than those specified in subparagraph (A)(i) may intervene to exercise authority, direction, or control over the Assistant Secretary in the discharge of such responsibilities. . (b) Modification of duties for Under Secretary of Defense for Acquisition and Sustainment Section 133b of title 10, United States Code, is amended— (1) in paragraph (5)— (A) in subparagraph (B), by striking ; and and inserting a semicolon; and (B) by adding after subparagraph (C), the following: (D) chairman of the Nuclear Weapons Council established by section 179 of this title; and (E) co-chairman of the Council on Oversight of the National Leadership Command, Control, and Communications System established by section 171a of this title; ; and (2) by amending paragraph (6) to read as follows: (6) overseeing— (A) the sustainment and modernization of United States nuclear forces, including the nuclear command, control, and communications system; and (B) military department and Defense Agency programs to develop capabilities to counter weapons of mass destruction