The crew of the Enola Gay pose in front of the B-29 Superfortress they used to drop “Little Boy,” an atomic bomb, on Hiroshima, Japan, helping to bring an early end to World War II. The Enola Gay was part of the 509th Composite Group, an organization within the 20th Air Force when it had a heavy bombardment mission. Now, the 20th AF maintains and operates the Air Force's ICBM force. (File photo)