The Argentine Naval Prefecture (Spanish: Prefectura Naval Argentina or PNA) is a service of the Argentine Security Ministry charged with protecting the country's rivers and maritime territory. It therefore fulfills the functions of other countries' coast guards, and furthermore acts as a gendarmerie force policing navigable rivers.
According to the Argentine Constitution, the Armed Forces of the Argentine Republic cannot intervene in internal civil conflicts, so the Prefecture is defined as a civilian «security force of a military nature». It maintains a functional relationship with the Ministry of Defense, as part of both the National Defense System and the Interior Security System. It therefore maintains capabilities arising from the demands required by joint military planning with the armed forces.
The PNA is a large organization for a coastguard. With a strength of 28,900 sworn members, the PNA is a larger organization than most national navies, and is in fact slightly larger than the Argentine Navy — the organization upon which it had been attached for a long time until the 1980s, when it was transferred to direct control of the Ministry of Defense.