In this chapter:

(1) The term “homeland defense activity” means an activity undertaken for the military protection of the territory or domestic population of the United States, or of infrastructure or other assets of the United States determined by the Secretary of Defense as being critical to national security, from a threat or aggression against the United States.

(2) The term “State” means each of the several States, the District of Columbia, the Commonwealth of Puerto Rico, or a territory or possession of the United States.