The Defense Threat Reduction Agency (DTRA) is a combat support agency of the U.S. Department of Defense, assigned the mission of safeguarding the United States and its allies from weapons of mass destruction (WMD - chemical, biological, radiological, nuclear and high-yield explosive weapons) by providing capabilities to reduce, eliminate, and counter the threat and mitigate its effects.

The Director of DTRA reports to the Under Secretary of Defense for Acquisition, Technology and Logistics, through the Assistant to the Secretary of Defense for Nuclear and Chemical and Biological Defense Programs. The DTRA Director also serves as the Director of the U.S. Strategic Command Center for Combating WMD, co-located with DTRA in the Defense Threat Reduction Center at Fort Belvoir, Va., and in this capacity reports to the Commander of U.S. Strategic Command.