National Steel and Shipbuilding Company, commonly referred to as NASSCO, is an American shipbuilding company with two shipyards located in San Diego, California and Norfolk, Virginia. It is a division of General Dynamics. The San Diego shipyard specializes in constructing commercial cargo ships and auxiliary vessels for the US Navy and Military Sealift Command; it is the only new-construction shipyard on the West Coast of the United States. The Virginia shipyard primarily performs ship repairs and conversions for the U.S.