The 497th Air Expeditionary Group is a provisional United States Air Force unit. It is assigned to Pacific Air Forces to activate or inactivate as needed.The unit was first activated in the United States Army Air Forces as the 497th Bombardment Group which was part of Twentieth Air Force during World War II. The 497th engaged in very heavy (B-29 Superfortress) bombardment operations against Japan and earned two Distinguished Unit Citations for its combat actions.