JP 3-28, page 12

Executive Summary x JP 3-28 appropriate authorities. DSCA is conducted only in the US homeland. Homeland Security, Homeland Defense, and Defense Support of Civil Authorities Homeland security (HS), homeland defense (HD), and DSCA are distinct operations. HS is a concerted national effort to prevent terrorist attacks within the US; reduce America’s vulnerability to terrorism, major disasters, and other emergencies; and minimize the damage and recover from attacks, major disasters, and other emergencies that occur. HD is the protection of US sovereignty, territory, domestic population, and critical infrastructure against external threats and aggression or other threats, as directed by the President. DOD is responsible for HD. DOD plays a vital role in all three missions involving the homeland—HD, HS, and DSCA. The key difference between the three missions is that DOD is responsible for the federal response to HD; DOD is in support of other federal agencies’ HS responsibilities; and DOD conducts DSCA operations in support of another primary agency supporting a state, local, territorial, or tribal response. DOD works with the Department of Homeland Security (DHS) and other United States Government (USG) departments and agencies to accomplish these missions. Fundamentals of Response State and local officials are responsible for preparing for and coordinating the provision of assistance to their populace for domestic emergencies and disasters. Governors have the authority to deploy and employ NG forces under their control in response to domestic incidents. NG forces in most situations will be employed under their control prior to requesting federal assistance; however, a governor may request federal assistance in parallel. The USG maintains a wide array of capabilities and resources that can be made available upon request of the governor of a state or local civil authorities for immediate response or under mutual aid agreements. When an incident occurs that exceeds or is anticipated to exceed state, local, or tribal resources, both neighboring states and the USG may provide resources and capabilities to support the response.