Argentine Naval Prefecture

The Argentine Naval Prefecture is a service of Argentina's 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.

Source: Wikipedia