Protecting the Homeland / Defense Support to Civil Authority Homeland Security 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. Homeland Defense 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. Defense Support of Civil Authorities (DSCA) is support provided 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. Disaster management (or emergency management) is the term used to designate the efforts of communities or businesses to plan for and coordinate all the personnel and materials required to either mitigate the effects of, or recover from, natural or man-made disasters, or acts of terrorism. The nature of DSCA in the US presents a unique challenge based on the history of the country and the interaction of the federal, state, local, territorial, and tribal governments and private and nonprofit organizations. US military personnel must understand the domestic environment so they can employ military capabilities efficiently, effectively, and legally. Topics and references include homeland defense (JP 3-28), defense support of civil authorities (JP 3-28), Army support of civil authorities (ADRP 3-28), multi-service DSCA TTPs (ATP 3-28.1/MCWP 3-36.2), DSCA liaison officer toolkit (GTA 90-01-020), key legal and policy documents, and specific hazard and planning guidance: wildland fires, wind storms, earthquakes & tsunamis, floods, winter storms, chemical biological radiation nuclear (CBRN) events, and national special security events (NSSE), plus more.