Assault Craft Unit ONE, (ACU-1) is a Pacific Ocean Maritime Prepositioning Force in the United States Navy operated under Naval Beach Group ONE out of Naval Amphibious Base (NAB) Coronado with a Forward Detachment in Sasebo, Japan. ACU-1's force consists of Landing Craft Utility (LCU) boats, Landing Craft Mechanized (LCM), Mark 8 boats , and Maritime Prepositioning Force Utility Boats (MPFUBs) . The sister unit of ACU-1 is Assault Craft Unit 2 in Naval Amphibious Base Little Creek, Virginia.