The Department of National Defense is the executive department of the Philippine government responsible for guarding against external and internal threats to peace and security in the country. The Department of National Defense exercises executive supervision over the Armed Forces of the Philippines (AFP), the Office of Civil Defense (OCD), the Philippine Veterans Affairs Office (PVAO), the National Defense College of the Philippines (NDCP), the Government Arsenal (GA), and Veterans Memorial Medical Center (VMMC). It is also responsible for disaster preparation and management in the country.

The Armed Forces of the Philippines (AFP) are the military forces of the Philippines. It consists of three main service branches; the Army, the Air Force, and the Navy. The President of the Philippines is the Commander-in-Chief of the AFP and forms military policy with the Department of National Defense, an executive department acting as the principal organ by which military policy is carried out, while the Chief of Staff of the Armed Forces of the Philippines serves as the overall commander and the highest-ranking officer in the AFP.