Homeland Defense is the protection of U.S. sovereignty, territory, domestic population, and critical defense infrastructure against external threats and aggression, or other threats as directed by the President. The Department of Defense is responsible for homeland defense.

Homeland Security is a concerted national effort to prevent terrorist attacks within the United States, reduce America's vulnerability to terrorism, and minimize the damage and recover from attacks that do occur. The Department of Homeland Security is the lead Federal agency for homeland security.

DoD roles within the United States:

Homeland Defense

• DoD exercises its core warfighting mission – to defend U.S. territory and interests
• Missions include: Maritime Interception Operations, Air Patrols over U.S. airspace, Land-based defense of critical infrastructure and assets, and Use of military forces, when directed by the President or Secretary of Defense, to protect the U.S. and territories from attack
• Threats can be from states or non-state actors

Defense Support of Civil Authorities (DSCA)

Defense Support of Civil Authorities

DoD support, including Federal military forces, the Department’s career civilian and contractor personnel, and DoD agency and component assets, for domestic emergencies and for designated law enforcement and other activities. The Department of Defense provides defense support of civil authorities when directed to do so by the President or the Secretary of Defense.

Protecting the United States homeland from attack is the highest priority of the Department of Defense (DoD).

To defeat 21st century threats, we must think and act innovatively. Our adversaries consider U.S. territory an integral part of global theater of combat.