<Li> Masters - at - Arms or MAs are enlisted Sailors of the U.S. Navy , designated as Naval Security Force ( NSF ) , primarily responsible for law enforcement and force protection . NSF personnel are led by Naval commissioned officers from the Limited Duty Officer ( LDO ) and Chief Warrant Officer ( CWO ) communities , who are also designated as NSF . Additionally , a host installation 's Security Force ( both overseas and in the Continental United States ) are augmented by Sailors on Temporary Assignment of Duty ( TEMADD ) from their parent units , as part of the Auxiliary Security Force ( ASF ) . Shore Patrol personnel are Sailors from U.S. naval vessels visiting foreign ports ( and some domestic ports ) assigned to the Shore Patrol Party or Beach Guard , responsible for the good order and discipline of Sailors from the visiting ship ( s ) on liberty . Sailors assigned to the Shore Patrol Party or Beach Guard Detachment do not include Sailors assigned to the ship 's Security Force , both performing different duties while visiting that country , because of the Status of Force Agreement ( SOFA ) and / or Rules of Engagement ( ROE ) . Prior to the 1970s , Master - at - Arms and Shore Patrol were used synonymously to refer to Sailors assigned to perform law enforcement and Shore Patrol duties . </Li>
what do military police do in the navy
primarily responsible for law enforcement and force protection