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). Not to be confused with Homeland security.
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:
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.