United States Atlantic Command (acronym from 1947-1993 USLANTCOM, after 1993 USACOM) was a Unified Combatant Command of the United States Department of Defense. In 1999, U.S. Atlantic Command was renamed and given a new mission as United States Joint Forces Command.USLANTCOM was active from the 1947 to 1993 as a primarily U.S. Navy command, focused upon the wartime defense of the Atlantic sea lanes against Soviet attack, with the U.S.