Defense Threat Reduction Agency
|Formed||October 1, 1998|
|Headquarters||Fort Belvoir, Virginia|
The Defense Threat Reduction Agency (DTRA) is an agency within the United States Department of Defense and is the official Combat Support Agency for countering weapons of mass destruction (chemical, biological, radiological, nuclear, and high explosives). DTRA's main functions are threat reduction, threat control, combat support, and technology development. The agency is headquartered in Fort Belvoir, Virginia. DTRA employs 1,850 civilian and military personnel at more than 14 locations around the world, including Russia, Kazakhstan, Azerbaijan, Uzbekistan, Georgia, and Ukraine.
DTRA was established in 1998 by consolidating several DoD organizations, including the Defense Special Weapons Agency (successor to the Defense Nuclear Agency) and the On-Site Inspection Agency as a result of the 1997 Defense Reform Initiative.
In 2005, the Secretary of Defense made the decision to designate the Commander, United States Strategic Command (USSTRATCOM) as the lead Combatant Command for the integration and synchronization of DoD’s Combating WMD efforts in support of U.S. government objectives. To fill this requirement, the USSTRATCOM Center for Combating Weapons of Mass Destruction was collocated with DTRA.
DTRA's vision is "to make the world safer by reducing the threat of weapons of mass destruction."
After the end of the Cold War, DTRA and its predecessor agencies have implemented the DoD aspects of several treaties that assist former Eastern Bloc countries in the destruction of Soviet era nuclear, biological, and chemical weapons sites (such as missile silos and plutonium production facilities) in an attempt to avert potential weapons proliferation in the post-Soviet era as part of the Nunn-Lugar Cooperative Threat Reduction program. DTRA is responsible for US reporting under the New START Treaty and the Intermediate-Range Nuclear Forces Treaty.
DTRA is also responsible for reducing the threat of conventional war, especially in Europe, by participating in various arms control treaties to which the United States is a party, such as the Conventional Forces in Europe treaty and the Treaty on Open Skies, as well as the Vienna Document and Global Exchange of Military Information under the auspices of the Organization for Security and Co-operation in Europe. the Transparency in Armaments activity of the United Nations, and the Wassenaar Arrangement.
In 2002, DTRA published a detailed history of its predecessor agencies, Defense’s Nuclear Agency, 1947–1997, which is in the public domain. The first paragraph of the preface makes the following brief statement about the agencies which led up to the formation of DTRA.
Defense’s Nuclear Agency, 1947–1997, traces the development of the Armed Forces Special Weapons Project (AFSWP), and its descendant government organizations, from its original founding in 1947 to 1997. After the disestablishment of the Manhattan Engineering District (MED) in 1947, AFSWP was formed to provide military training in nuclear weapons’ operations. Over the years, its sequential descendant organizations have been the Defense Atomic Support Agency (DASA) from 1959 to 1971, the Defense Nuclear Agency (DNA) from 1971 to 1996, and the Defense Special Weapons Agency (DSWA) from 1996 to 1998. In 1998, DSWA, the On-Site Inspection Agency, the Defense Technology Security Administration, and selected elements of the Office of Secretary of Defense were combined to form the Defense Threat Reduction Agency (DTRA).
On January 26, 2006, the director of DTRA was given the extra responsibility of the director of the USSTRATCOM Center for Combating Weapons of Mass Destruction, a subordinate component to the U.S. Strategic Command. 
DTRA has the responsibility to manage and integrate the Department of Defense chemical and biological defense science and technology programs. In accordance with the Recommendation 174 (h) of the 2005 Base Closure and Realignment Commission, part of the Chemical Biological Defense Research component of the Defense Threat Reduction Agency was re-located to Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland in 2011.  This represented a move of about ten percent of the staff of the Chemical Biological Defense Research component of DTRA to Aberdeen Proving Ground; the rest of the staff remain at Fort Belvoir.
DTRA sponsors the journal WMD Insights, while The Shield is the official magazine of the DTRA SCC-WMD, and is printed quarterly.
- "Department of Defense Reform Initiative Directive #6 - Appointment of the Team to Create the Defense Threat Reduction and Treaty Compliance Agency". Office of the Secretary of Defense. 3 December 1997. Retrieved July 30, 2011.
- "Defense Threat Reduction Agency Operation and Maintenance, Defense-Wide Fiscal Year (FY) 2015 Budget Estimates" (PDF). DoD. March 2014. Retrieved July 8, 2015.
- "Defense's Nuclear Agency, 1947–1997" (PDF). DTRA History Series. 2002. Retrieved October 9, 2010.
- "Responding to War, Terrorism and WMD Proliferation: History of DTRA, 1998 – 2008" (PDF). DTRA History Series. 2008. Retrieved September 21, 2011.
- "DoD Directive 5160.05e, Roles and Responsibilities Associated with the Chemical and Biological Defense (CBD) Program (CBDP)" (PDF). DoD. October 9, 2008. Retrieved July 30, 2011.
- "Appendix Q, Commission's Final Recommendations, page Q-82" (PDF). DoD. September 8, 2005. Retrieved July 30, 2011.
- "BRAC Implementation Package Description" (PDF). DoD Comptroller. Retrieved October 1, 2011.
- "The Shield" (PDF). DTRA. Retrieved September 21, 2011.
- DTRA, the official web site of the Defense Threat Reduction Agency
- Responding to War, Terrorism, and WMD Proliferation: History of DTRA, 1998–2008, DTRA History Series
- WMD Insights, DTRA supported journal
- "The Shield", DTRA's official magazine
- Defense's Nuclear Agency, 1947–1997, DTRA History Series
- CNTTR, The Center for NBC Threats, Technology Transfer, and Resources of the Defense Threat Reduction Agency
- ACE Center, The Assessment of Catastrophic Events Center of the Defense Threat Reduction Agency