Korean War Minesweeping. Four U.S. Navy minesweepers (AMS) tied up at Yokosuka, Japan, following mine clearance activities off Korea. Original photo is dated 30 November 1950. These four ships, all units of Mine Division 31, are (from left to right): USS Merganser (AMS-26); USS Osprey (AMS-28); USS Chatterer (AMS-40) and USS Mockingbird (AMS-27). Ship in the extreme left background is USS Wantuck (APD-125).