The DEST provides guidance to the FBI Special Agent in Charge (SAC) concerning weapons of mass destruction (WMD) threats and actual incidents/attacks.
The Secretary of Defense authorizes the deployment of the DEST aircraft and all DoD personnel assigned to the team.
[2] The DEST is incorporated directly into the existing on-site FBI crisis management structure to advise the On Scene Commander (OSC) of federal-level capabilities that can be brought to bear on the incident.
The Domestic Emergency Support Team was originally created under Presidential Decision Directive 39 (PDD 39), "U.S. Policy on Counterterrorism," signed by President Bill Clinton on June 21, 1995.
That document called for a "rapidly deployable interagency emergency support team" to assist the Federal Bureau of Investigation (FBI) during domestic terrorist events involving the use of chemical, biological, radiological, nuclear, or explosive weapons.