The female commanding officer of a Navy amphibious ship quit her command on Monday, according to a report, in a highly unusual move for a CO.

Navy Times reported that Cmdr. Sarah DeGroot walked away from command of the dock landing ship Rushmore on Monday. But three sources were unable to tell the newspaper specifically why DeGroot told Capt. Homer Denius, the head of Amphibious Squadron 3, why she was giving up command.