Dr. Rhys M. Williams, a Tier 3 member of the career Senior Executive Service, is the Executive Director of the Defense Threat Reduction Agency (DTRA). In this role, he serves as the Agency’s senior civilian and Chief Operating Officer overseeing 2,100 military and civilian experts operating in over 50 countries. Dr. Williams manages the execution of over $2.4B to provide the Department of Defense's Service Components, Combatant Commands, the U.S. Interagency, and international partners with leading-edge capabilities to counter and deter adversary use of Weapons of Mass Destruction and emerging threats.

Prior to assuming his current position, Dr. Williams served as the Acting Director of DTRA from January 2021 through April 2022. During this time he led all Agency efforts in support of US military operations and activities, partner engagement and support to the broader US government.

Previously, he served as the Agency’s Director for research, development, test, and evaluation activities where he led a geographically-dispersed military and civilian workforce of more than 450 Ph.D. level engineers and scientists and executed an annual budget of more than $1 billion. Dr. Williams led the Department of Defense’s primary science and technology (S&T) program to develop capabilities to detect, deter, and defeat foreign chemical, biological, radiological, and nuclear Weapons of Mass Destruction (WMD), as well as emerging threats. As one of the S&T Executives for DoD, Dr. Williams was the senior Agency S&T interface with the Military Services and the DoD, Office of the Undersecretary of Defense for Research and Engineering (USD(R&E)).

Dr. Williams previously served as the Assistant Deputy Administrator for Defense Nuclear Nonproliferation R&D at the U.S. Department of Energy’s National Nuclear Security Administration (NNSA). In addition, he also served as Acting Principle Deputy Administrator for Defense Nuclear NonProlfieration within NNSA.

Dr. Williams specializes in issues at the intersection of technology development and national security policy. He led policy, R&D, analytical, and operational organizations in both the public and private sectors with a specific focus on nonproliferation and counterproliferation activities.

Dr. Williams holds a Bachelor of Science in Engineering Physics from Miami University; a Master of Arts in International Science and Technology Policy from the Elliott School of International Affairs at George Washington University; and a Ph.D. in Public Policy, with an emphasis in science and technology policy in a national security context from the School of Public Policy, George Mason University. A former submarine officer, Dr. Williams was qualified as a nuclear power plant manager through the Naval Nuclear Propulsion Program and also served as a nuclear weapons officer. He is the author of a number of publications, including a National Intelligence Estimate. Dr. Williams is a level 3 acquisition professional and the recipient of a Presidential Rank Award.