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 Coronado with a Forward Detachment in Sasebo, Japan. ACU-1's force consists of Landing Craft Utility boats (LCU), Landing Craft Mechanized, Mark 8 boats (LCM), and Maritime Prepositioning Force Utility Boats (MPFUB). The sister unit of ACU-1 is Assault Craft Unit 2 in Naval Amphibious Base Little Creek, Virginia.