The Federal Emergency Management Agency, or FEMA, is an agency of the United States Department of Homeland Security. The purpose of FEMA (begun by Presidential Order on April 1, 1979) See Federation of American Scientists reference above for effective date of April 1, 1979 stated in Executive Order 12127. is to coordinate the response to a disaster which has occurred in the United States and which overwhelms the resources of local and state authorities. The governor of the state in which the disaster occurred must declare a state of emergency and formally request from the President that FEMA and the federal government respond to the disaster. The only exception is when an emergency or disaster occurs on federal property or to a federal asset, for example, the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, in the 1995 bombing, or the Space Shuttle Columbia in the 2003 return-flight disaster.

While on-the-ground support of disaster recovery efforts is a major part of FEMA's charter, the agency provides state and local governments with experts in specialized fields and funding for rebuilding efforts and relief funds for individual citizens and infrastructure, in conjunction with the Small Business Administration. FEMA also assists individuals and businesses with low interest loans. In addition to this, FEMA provides funds for training of response personnel throughout the United States and its territories as part of the agency's preparedness effort.