The military defense of Puerto Rico is the responsibility of the United States as part of the Treaty of Paris. Locally, Puerto Rico has its own National Guard, the Puerto Rico National Guard, and its own state defense force, the Puerto Rico State Guard, which, by local law, is under the authority of the Puerto Rico National Guard. The commander-in-chief of both forces is the governor of Puerto Rico, currently Pedro Pierluisi, who delegates his authority to the Puerto Rico Adjutant General, currently Major General José J. Reyes. The Adjutant General, in turn, delegates the authority over the State Guard to another officer but retains the authority over the Puerto Rico National Guard as a whole. At the national level, the commander-in-chief is the President of the United States, currently Joe Biden.

Ramey Air Force Base also known as Borinquen Field, is a former United States Air Force base in Aguadilla, Puerto Rico. It was named after United States Army Air Forces Brigadier General Howard Knox Ramey. Following its closure, it was redeveloped into Rafael Hernandez Airport.