Homeland defense
Homeland defense (HD) is the protection of a territory, sovereignty, domestic population, and critical infrastructure against external threats and aggression. (Definition will be incorporated into JP 3-26 upon its approval).

Homeland security (HS) is a concerted national effort to prevent terrorist attacks, reduce a nation's vulnerability to terrorism, and minimize the damage and recover from attacks that do occur.

Full definition
"Homeland defense (HD) is the protection of a sovereignty, territory, domestic population, and critical defense infrastructure against external threats and aggression, or other threats as directed
by the leader of that nation such as the President of the United States. The United States Department of Defense is partially responsible for the Homeland defense mission of the United States, and therefore leads the HD response, with other departments and agencies in support of DOD efforts."

Threat strategy
HD strategic threat environment is based on the following conditions and profiles:
Diminished protection afforded by geographic distances
Traditional threats remain
Greater risk of a weapon of mass destruction attack
Increased potential for miscalculation and surprise
Increased potential for terrorist attacks
Increased challenges from weak and failing states and non-state actors
Increasing diversity in sources and unpredictability of the locations of conflict
Threats to US vital interests overseas
Increasing transnational.
Responses to the changes in any of the above can affect US's international environment through the application of diplomatic, economic, military, and informational means. Thus, a proactive and comprehensive approach to HD is required for US's response.

See also
National Strategy for Homeland Security
Air Forces Northern National Security Emergency Preparedness Directorate

References

External links
Homelanddense.com Homeland Defense Solutions
Pentagon Library: Homeland Defense

Civil defense
Law enforcement in the United States
American political neologisms