( CNN ) An American naval cargo ship has run aground off the Japanese coast , east of Okinawa , and efforts are underway to refloat it , the U.S. Navy said Thursday . `` The safety of the civilian crew members and the environment are our top priorities . So we 're taking this situation very seriously and will continue to investigate the situation until it 's resolved , '' said Cmdr . William Marks , spokesman for the U.S. Navy 7th Fleet . Last mission for storied class of warships . The U.S. Navy identified the ship as the Military Sealift Command prepositioning vessel USNS Sgt . Matej Kocak . The Navy said it was stuck 6 nautical miles off Uruma , on the island of Okinawa . `` The ship is stable right now , '' Marks said . `` Any water found in the ship is just from the normal tide going in and out . '' Tugs were at the location , assessing the best way to free the vessel in conjunction with the Japanese . `` The U.S. Navy is working closely with Japanese authorities to assess the situation and determine the best course of action to refloat the vessel , '' the Navy said . `` No leaks from the hull have been found and no damage to the surrounding area has been reported . '' The ship carries 131 crew members -- 38 civilians and 67 Army and 26 Marine Corps personnel , the Navy said . All were unhurt and still on board , it said . The Military Sealift Command operates more than 100 noncombat , civilian crew ships that service the Defense Department in specialized missions , according to its website . CNN 's Will Ripley reported from Tokyo , and Brian Walker wrote from Atlanta .
A cargo ship has run aground 30 nautical miles off the coast of Uruma , Japan . No one was hurt , and crew were on board , U.S. Navy says .