Assistant Secretary of Defense for Nuclear, Chemical & Biological Defense Programs

Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs
Emblem of the assistant secretary of defense for nuclear, chemical and biological defense programs
Flag of an assistant secretary of defense
Incumbent Drew Walter [1] Acting   since May 26, 2025 [2]
Office of the Secretary of Defense
Style	Sir/Madam Assistant Secretary (formal address in writing)
Reports to	Under Secretary of Defense for Acquisition and Sustainment Deputy Secretary of Defense United States Secretary of Defense
Appointer	The president with the advice and consent of the Senate
Term length	No fixed term
Formation	2009
Succession	16th in SecDef succession
Deputy	The deputy under secretary
Salary	Level IV of the Executive Schedule
Website	www.acq.osd.mil/ncbdp

The assistant secretary of defense for nuclear, chemical and biological defense programs, or ASD(NCB), is the principal adviser to the secretary of defense, deputy secretary of defense and the under secretary of defense for acquisition and sustainment on policy and plans for nuclear, chemical, and biological defense programs.

Duties

The assistant secretary of defense for nuclear, chemical and biological defense programs develops policies, advice, and recommendations on nuclear energy, nuclear weapons, and chemical and biological defense, including:

• nuclear weapons;
• chemical, biological, radiological, and nuclear (CBRN) medical and non-medical defense;
• safety and security of chemical and biological agents;
• safety, surety, security, and safe destruction of the current chemical weapon stockpile;
• nuclear, chemical and biological arms control activities and related plans and programs.

The assistant secretary of defense for nuclear, chemical & biological defense programs also serves as DoD coordinator and funding administrator for nuclear and conventional physical security equipment research, development, test, and evaluation programs executed by the Military Departments and the Defense Threat Reduction Agency (DTRA). ^[3]

Before the National Defense Authorization Act for Fiscal Year 2011 on January 7, 2011, the assistant secretary of defense for nuclear, chemical and biological defense programs was known as the "assistant to the secretary of defense for nuclear and chemical and biological defense programs". ^[4]

Three deputy assistant secretaries of defense report to the assistant secretary of defense for nuclear chemical and biological defense programs:

• the deputy assistant secretary of defense for chemical and biological defense (DASD(CBD))
• the deputy assistant secretary of defense for nuclear matters (DASD(NM))
• the deputy assistant secretary of defense for threat reduction and arms control (DASD(TRAC))

In addition, the director of the Defense Threat Reduction Agency reports directly to the assistant secretary of defense for nuclear, chemical and biological defense programs.

Subordinates

The deputy assistant secretary of defense for chemical and biological defense executes day-to-day management, governance, and resourcing of the Chemical and Biological Defense Program (CDBP) and coordinates with the Executive Agent (EA) for Chemical and Biological Defense (CBD) and other Office of Secretary of Defense components using the procedures and governance framework in DoDI 5160.01.

The deputy assistant secretary of defense for chemical and biological defense oversees development of chemical, biological, radiological and nuclear (CBRN) defenses to protect national interests at home and abroad, handling Department of Defense efforts related to:

• science and technology,
• advanced development
• test and evaluation of chemical, biological, radiological and nuclear defenses
• the Chemical and Biological Defense Program Objective Memorandum (POM). ^[5]

The deputy assistant secretary for nuclear matters is primarily the focal point for activities and initiatives related to sustaining a safe, secure, and effective nuclear deterrent and countering threats from nuclear terrorism and nuclear proliferation. This office serves as a primary point of contact for Congress, other agencies, and the public for those programs.

The deputy assistant secretary for nuclear matters (DASD(NM)) fulfills the nuclear weapons roles, responsibilities, and functions for the assistant secretary of defense for nuclear, chemical and biological defense programs (ASD(NCB)).  The Office of the Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs/Nuclear Matters (OASD(NCB/NM)) is the focal point of the Department of Defense for the U.S. nuclear deterrent. In this capacity, nuclear matters is the primary DoD point of contact for Congress, the interagency, and the public and for allies and foreign partners on issues related to the U.S. nuclear stockpile and the integration and alignment of U.S. nuclear weapons and weapons systems. To perform these functions, nuclear matters is composed of representatives from all areas of the nuclear community, including the U.S. Navy, the U.S. Air Force, the National Guard Bureau, the United States Nuclear Command and Control Systems Support Staff, the Defense Threat Reduction Agency, the Department of Energy, the National Nuclear Security Agency, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sandia National Laboratories, the Kansas City Plant, and the National Security Agency. ^[6]

The deputy assistant secretary of defense for threat reduction and arms control is the principal adviser to the assistant secretary for defense for nuclear, chemical and biological defense programs for

• acquisition oversight, implementation, and compliance with nuclear, biological, and chemical treaties;
• cooperative threat reduction; chemical demilitarization programs;
• building global partner capacity to counter weapons of mass destruction.

The OASD(NCB/TRAC) exercises oversight of the Defense Threat Reduction and Agency-executed Cooperative Threat Reduction Program and provides oversight of the Chemical Demilitarization Program. ^[7]

This office also:

• oversees implementation of and compliance with existing and prospective nuclear, biological, and chemical arms control agreements in accordance with DoDD 2060.1;
• integrates programs to combat proliferation weapons of mass destruction; and
• assists the Deputy Assistant Secretary of Defense for Nuclear, Chemical & Biological Defense Programs as Executive Secretary of the Counterproliferation Program Review Committee (CPRC) and Chair of the Standing Committee of the CPRC. ^[8]

History

The Office of the Assistant Secretary of Defense for Nuclear, Chemical & Biological Defense Programs' functions can be traced back to the US Department of Defense's Military Liaison Committee (MLC), formed in the early Cold War to coordinate military requirements with the United States Atomic Energy Commission. The MLC was the channel of communication between the DoD and AEC (and later, the US Energy Research and Development Administration and the US Department of Energy) on all matters relating to military applications of atomic weapons or atomic energy. It addressed matters of policy, programming, and funding of the military application of atomic energy. ^[9]

In 1951, the secretary of defense moved the Military Liaison Committee to the Pentagon. Its chairman became the deputy to the secretary of defense for atomic energy matters. In 1953, this position was renamed the assistant to the secretary of defense for atomic energy. ^[9]

The National Defense Authorization Act for Fiscal Year 1987 (P.L. 99-661, passed in November 1986) abolished the Military Liaison Committee, replacing it with the Nuclear Weapons Council. Just over a year later, the National Defense Authorization Act for Fiscal Years 1988–1989 (P.L. 100-180) created the position of Assistant to the Secretary of Defense (Atomic Energy). ^[10]

In 1994, the assistant to the secretary of defense (atomic energy) was given control over the Defense Nuclear Agency (DNA), which became the Defense Threat Reduction Agency. ^[9] In February 1996, the National Defense Authorization Act for Fiscal Year 1996 (P.L. 104-106) officially created the office of the assistant to the secretary of defense for nuclear and chemical and biological defense programs, or ASTD (NCB) to replace that of the assistant to the secretary of defense (atomic energy). ^[10]

The Clinton administration declined to nominate an assistant to the secretary of defense for nuclear and chemical and biological defense programs between 1997 and 2001, having determined (as part of its Defense Reform Initiative) that the position should be eliminated. Congress insisted that the Pentagon maintain the office, arguing it was necessary to ensure appropriate senior-level policy oversight and implementation guidance within the Department of Defense. ^[9]

In January 2011, President Obama signed the National Defense Authorization Act for FY 2011, renaming the assistant to the secretary of defense for nuclear and chemical and biological defense programs the assistant secretary of defense for nuclear, chemical and biological defense programs. ^[4]

Officeholders

The table below includes both the various titles of this post over time, as well as all the holders of those offices.

Assistants to the secretary of defense (nuclear and chemical and biological defense programs) ^[10]

Name	Tenure	SecDef(s) served under	President(s) served under
Chairman, Military Liaison Committee
Lt. Gen. Lewis H. Brereton (USA)	July 17, 1947 – March 30, 1948	James V. Forrestal	Harry Truman
Donald F. Carpenter	April 8, 1948 – September 21, 1948	James V. Forrestal	Harry Truman
William Webster	September 22, 1948 – September 30, 1949	Louis A. Johnson	Harry Truman
Robert LeBaron	October 1, 1949 – April 12, 1953	Louis A. Johnson George C. Marshall, Jr. Robert A. Lovett Charles E. Wilson	Harry Truman Dwight Eisenhower
Chairman, Military Liaison Committee/Assistant to the Secretary of Defense (Atomic Energy)
Robert LeBaron	April 13, 1953 – August 1, 1954	Charles E. Wilson	Dwight Eisenhower
Maj. Gen. Herbert B. Loper (USAF)	August 9, 1954 – July 14, 1961	Charles E. Wilson Neil H. McElroy Thomas S. Gates Robert S. McNamara	Dwight Eisenhower John F. Kennedy
Dr. Gerald W. Johnson	August 11, 1961 – September 15, 1963	Robert S. McNamara	John F. Kennedy
William J. Howard	January 2, 1964 – June 15, 1966	Robert S. McNamara	Lyndon Johnson
Dr. Carl Walske	October 3, 1966 – April 15, 1973	Robert S. McNamara Clark M. Clifford Melvin R. Laird Elliot L. Richardson	Lyndon Johnson Richard Nixon
Donald R. Cotter	October 16, 1973 – March 17, 1978	James R. Schlesinger Donald H. Rumsfeld Harold Brown	Richard Nixon Gerald Ford Jimmy Carter
Dr. James P. Wade, Jr.	August 8, 1978 – June 14, 1981 June 15, 1981 – June 5, 1982 (Acting)	Harold Brown Caspar W. Weinberger	Jimmy Carter Ronald Reagan
Dr. Richard Wagner	June 6, 1982 – April 1, 1986	Caspar W. Weinberger	Ronald Reagan
Dr. Robert B. Barker	October 18, 1986 – November 14, 1986	Caspar W. Weinberger	Ronald Reagan
Assistant to the Secretary of Defense (Atomic Energy)
Dr. Robert B. Barker	November 14, 1986 – March 3, 1988 (non-statutory) March 4, 1988 – May 29, 1992 (statutory)	Caspar W. Weinberger Frank C. Carlucci III William H. Taft IV (Acting) Richard B. Cheney	Ronald Reagan George H. W. Bush
Dr. John Birely (Acting)	May 29, 1992 – May 6, 1993	Richard B. Cheney Leslie Aspin, Jr.	George H. W. Bush William Clinton
Dr. Harold P. Smith, Jr.	June 1, 1993 – March 10, 1996	William J. Perry	William Clinton
Assistant to the Secretary of Defense (Nuclear & Chemical & Biological Defense Programs)
Dr. Harold P. Smith, Jr.	March 11, 1996 – January 31, 1998	William J. Perry William S. Cohen	William Clinton
Position Vacant	1998–2001	William S. Cohen	William Clinton George W. Bush
Dr. Dale Klein [9]	November 15, 2001 – June 30, 2006	Donald H. Rumsfeld	George W. Bush
Dr. A. Thomas Hopkins (Acting) [9]	June 30, 2006 – July 8, 2008	Donald H. Rumsfeld Robert M. Gates	George W. Bush
Fred Celec [9]	July 8, 2008 – May 18, 2009	Robert M. Gates	George W. Bush Barack Obama
Andrew C. Weber [3]	May 18, 2009 – January 7, 2011	Robert M. Gates	Barack Obama
Assistant Secretary of Defense (Nuclear, Chemical & Biological Defense Programs)
Andrew C. Weber	January 7, 2011 – October 1, 2014	Robert M. Gates Leon Panetta Chuck Hagel	Barack Obama
Dr. A Thomas Hopkins (Acting)	October 1, 2014 – November 29, 2017	Ash Carter	Barack Obama
Guy B. Roberts	November 30, 2017 – April 2, 2019	Jim Mattis	Donald Trump
Alan Shaffer (PTDO)	April 2, 2019 – January 20, 2021	Mark Esper	Donald Trump
Dr. Brandi Vann (Acting)	January 20, 2021 – August 4, 2021	Lloyd Austin	Joe Biden
Deborah G. Rosenblum	August 4, 2021 – April 8, 2024	Lloyd Austin	Joe Biden
Dr. Brandi Vann (Acting)	April 8, 2024 – May 26, 2025	Lloyd Austin Pete Hegseth	Joe Biden Donald Trump
Drew Walter (Acting)	May 26, 2025 – Present	Pete Hegseth	Donald Trump

References

1. https://www.acq.osd.mil/ncbdp/leadership/bio-walter.html ^{[ bare URL ]}
2. United States Department of Defense
3. "Defense.gov Biography: Andrew C. Weber". Archived from the original on 2012-07-13. Retrieved 2012-06-10.
4. H.R. 6523, Title IX, Subtitle A, 5 January 2011, http://www.gpo.gov/fdsys/pkg/BILLS-111hr6523enr/pdf/BILLS-111hr6523enr.pdf
5. "Nuclear Chemical and Biological Defense Programs: Organization". Office of the Under Secretary of Defense for Acquisition, Technology and Logistics. Archived from the original on 3 February 2016. Retrieved 3 February 2016. This article incorporates text from this source, which is in the public domain .
6. "OASD(NCB/NM)". www.acq.osd.mil. Retrieved 2021-03-25.
7. "OASD(NCB/TRAC)". www.acq.osd.mil. Retrieved 2021-03-25.
8. "OASD(NCB)". www.acq.osd.mil. Retrieved March 25, 2021.
9. Office of the Deputy Assistant to the Secretary of Defense for Nuclear Matters, "NM History" "NM History". Archived from the original on March 30, 2010. Retrieved February 3, 2011.
10. "Department of Defense Key Officials" (PDF). Historical Office, OSD. 2004. Archived from the original (PDF) on July 21, 2011. Retrieved February 1, 2011.