This is a list of yard and district craft of the United States Navy. It covers the various types of craft and ships that support the bases and harbors of the United States Navy. The hull classification symbols for these craft begin with (Y). The District Auxiliary, Miscellaneous (YAG) designation has been used as a cover for at least two ships employed in classified tests of biological, chemical, and nuclear weapons (aka WMD). Some of these vessels have held prior or later classifications as unclassified miscellaneous (IX), or more rarely as auxiliaries miscellaneous (AG, T-AG).