What does homeland defense entail?

Homeland defense encompasses the protection of U.S. territory from potential external military attacks, thereby ensuring the safety and security of the nation from threats that originate outside its borders. This concept primarily focuses on the military aspect of national security, emphasizing the need for a robust defense system to deter or respond to threats posed by foreign nations or hostile entities. The activities involved in homeland defense may include readiness measures, intelligence gathering, and coordination among various defense entities to safeguard critical infrastructures and the general populace.

In this context, the other options do not fully capture the scope of homeland defense. While protecting against domestic terrorism represents an important aspect of national security, it falls under the broader category of homeland security rather than homeland defense, which is specifically concerned with military threats. Similarly, protecting military installations is part of a larger homeland defense framework but does not define its entirety. Surveillance of foreign threats is also critical, yet it is merely one proactive measure taken within the broader spectrum of homeland defense rather than the primary focus itself.