JP 3-28, page 39

Supporting a Comprehensive All Hazards Response II-5 c. Regardless of the type of incident, the President leads the USG response effort to ensure the necessary resources are applied quickly and efficiently to large-scale and catastrophic incidents. Different USG departments or agencies lead coordination of the USG’s response, depending on the type and magnitude of the incident, and are also supported by other agencies that bring their relevant capabilities to bear in responding to the incident. For example, FEMA leads and coordinates federal response and assistance when the President declares a major disaster or emergency under the Stafford Act. Similarly, the Department of Health and Human Services leads all federal public health and medical response to public health emergencies and incidents covered by the NRF. d. The response to a catastrophic incident, and any cascading effects, requires a coordinated effort involving local, state, tribal, territorial, and federal governments; NGOs; and private sector partners. All response partners, organized in support of an ESF, utilize NIMS to facilitate usage of a common terminology, including the establishment of plain language (clear text) communications standards, accessible and actionable effective communication for whole community access, integrated communications, unified command structure, and comprehensive resource management to ensure effective coordination between all stakeholders. 3. Department of Defense Immediate Response and Emergency Authority a. Immediate Response. As authorized by the Stafford Act, and prescribed by DODD 3025.18, Defense Support of Civil Authorities (DSCA), federal military commanders, heads of DOD components, and responsible DOD civilian officials have immediate response authority. In response to an RFA from a civil authority, under imminently serious conditions and if time does not permit approval from higher authority, DOD officials may provide an immediate response by temporarily employing the resources under their control, subject to any supplemental direction provided by higher headquarters, to save lives, prevent human suffering, or mitigate great property damage within the US. Immediate response authority is not an exception to the PCA nor does it permit actions that would subject civilians to the use of military power that is regulatory, prescriptive, proscriptive, or compulsory. (1) A DOD official directing immediate response authority shall immediately notify, through the chain of command, the National Joint Operations and Intelligence Center (NJOIC). The NJOIC will inform United States Northern Command (USNORTHCOM) and/or United States Indo-Pacific Command (USINDOPACOM) and the appropriate DOD components. (2) Immediate response ends when DOD assistance is no longer necessary (e.g., when there are sufficient resources and capabilities available from state, local, and other federal agencies to respond adequately) or when a DOD authority directs an end to the response. The DOD official directing a response under immediate response authority makes an assessment, no later than 72 hours after receipt of request for DOD assistance, as to whether there remains a need for the continued DOD support. Under Title 42, USC, DOD response may not exceed 10 days without presidential approval.