JP 3-0, page 135

Joint Operations Across the Range of Military Operations V-29 (2) Defense Support of Civil Authorities. Support provided by US federal military forces, DOD civilians, contract personnel, component assets, and National Guard forces (when SecDef, in coordination with the Governors of the affected states, elects and requests to use those forces in Title 32, USC status) in response to requests for assistance from civil authorities for domestic emergencies, law enforcement support, and other domestic activities, or from qualifying entities for special events. For DSCA operations, DOD supports and does not supplant civil authorities. Within a state, that state’s governor is the key decision maker. (a) The majority of DSCA operations are conducted in accordance with the NRF. The NRF establishes a comprehensive, national, all-hazards approach to domestic incident response. The NRF identifies the key response principles, as well as the roles and structures that organize national response. It describes how communities, states, the USG and private-sector and nongovernmental partners apply these principles for a coordinated, effective national response. In addition, it describes special circumstances where the USG exercises a larger role, including incidents where federal interests are involved and catastrophic incidents where a state would require significant support. It lays the groundwork for first responders, decision makers, and supporting entities to provide a unified national response. DOD provides this support with the stipulation that it does not conflict with DOD’s mission or its ability to respond to military contingencies. (b) Other DSCA operations can include CD activities, incident awareness and assessment or investigative support, or other support to civilian law enforcement in accordance with specific DOD policies and US law. (3) Global Perspective. Commander, US Northern Command, and Commander, US Pacific Command, have specific responsibilities for HD and DSCA. These responsibilities include conducting operations to deter, prevent, and defeat threats and aggression aimed at the United States, its territories, and interests within their assigned AORs, as directed by the President or SecDef. However, DOD support to HD is global in nature and is often conducted by all CCDRs beginning at the source of the threat. In the forward regions outside US territories, the objective is to detect and deter threats to the homeland before they arise and to defeat these threats as early as possible when so directed. For detailed guidance on CS, see JP 3-28, Civil Support, and for more detailed guidance on DSCA, see DODD 3025.18, Defense Support of Civil Authorities. For detailed guidance on HD, see JP 3-27, Homeland Defense. 9. Other Considerations a. Duration and End State. Crisis response and limited contingency operations may last for a relatively short period of time (e.g., NEO, strike, raid) or for an extended period of time to attain the national strategic end state (such as US participation with ten other nations in the independent [non-UN] peacekeeping operation, Multinational Force and Observers, in the Sinai Peninsula since 1982). Short duration operations are not