Overview :
Homeland security refers to a national effort to prevent terrorist attacks within the U.S., reduce America’s vulnerability to terrorism, and, for attacks that do occur, to minimize damage and facilitate a quick recovery. Homeland defense is the protection of U.S. territory, sovereignty, domestic population, and critical infrastructure against external threats and aggression. Homeland “security” usually connotes the civilian aspect of this effort whereas homeland “defense” refers to the military aspect.
Included within the purview of homeland security are emergency preparedness, intelligence activities, critical infrastructure protection, border security, transportation security, bio-defense, and the detection of radioactive/radiological materials.