sentences:  While the alterations were still in progress, Imperial Japanese Navy aircraft attacked Pearl Harbor, Hawaii on 7 December 1941, plunging the United States into World War II.Placed in service on 3 January 1942, "Viking" was pronounced ready for duty on 12 February 1942.Manned by a civilian crew and operated from San Diego by the Merritt, Chapman, and Scott salvage firm – a civilian company working under a contract let by the U.S. Navy Bureau of Ships – "Viking" was assigned to the 11th Naval District.