DTRA is the youngest agency in the Department of Defense, but in a way it is also the oldest, pre-dating the Department itself. The agency was created in 1998 from a number of other entities to focus their efforts on terrorism, our own nuclear surety, and counterproliferation, but DTRA’s rich legacy extends back to the Manhattan Engineering Project that was created to develop the world’s first atomic bomb during World War II.
After the war, the Manhattan Project continued working on atomic weapons until the Atomic Energy Act of 1946 split the program into two parts: The Atomic Energy Commission (today's Department of Energy) and the Armed Forces Special Weapons Project (AFSWP). The AFSWP was established to conduct military training in nuclear weapon operations. The organization changed over the years (Armed Forces Special Weapons Project, 1947-1959, Defense Atomic Support Agency, 1959-1971, Defense Nuclear Agency, 1971-1996, Defense Special Weapons Agency 1996-1998) and was called the Defense Special Weapons Agency, the Department of Defense’s center for nuclear and advanced weapons effects expertise, when it was combined with other WMD-related agencies and programs in 1998 to form DTRA.
Another DTRA legacy organization is the On-Site Inspection Agency, formed in 1988 to carry out the on-site inspection and escorting responsibilities of the U.S. government under the Intermediate-Range Nuclear Forces Treaty. For a time, the Director of DTRA was also dual-hatted as the director of the Defense Technology Security Administration, which was formed in 1985 as a field activity under the Office of the Under Secretary of Defense for Policy to manage the Department of Defense’s license review process for the export of dual-use technologies and munitions. That organization eventually returned to the Pentagon.
One of the biggest elements that became part of DTRA in 1998 was the Nunn-Lugar Cooperative Threat Reduction program office, which transferred from the Office of the Assistant to the Secretary of Defense for Nuclear, Chemical and Biological Defense Programs. Its mission at the time was to assist the nations of the former Soviet Union in reducing their weapons of mass destruction subject to international arms control treaties. The Office of the Secretary of Defense program management office for Chemical-Biological Defense programs also was transferred into DTRA.
From 2005 to 2016, the U.S. Strategic Command Center for Combating Weapons of Mass Destruction (SCC-WMD) was co-located with DTRA on Fort Belvoir. The Secretary of Defense directed STRATCOM to lead the CWMD integration and synchronization efforts, and the SCC-WMD was the STRATCOM element in charge of those efforts; during this time, the DTRA Director was also the director of the SCC-WMD. In 2016, this responsibility was transferred from STRATCOM to U.S. Special Operations Command (SOCOM), and the hand-off from STRATCOM to SOCOM was completed in early 2017.
DTRA grew again in 2016 when the Joint Improvised-Threat Defeat Agency (JIDA) was renamed the Joint Improvised-Threat Defeat Organization (JIDO) in accordance with the 2016 National Defense Authorization Act and became a part of DTRA. Originally formed to address the threats posed by Improvised Explosive Devices (IEDs) in Iraq and Afghanistan, JIDO's mission is to enable the DoD to very quickly address and counter improvised threats, including IEDs, car bombs, armed drones, and more.