Intercontinental ballistic missiles have only been a part of the Air Force since the late 1950s. As a result, many ICBM wings and squadrons were assigned the unit designation numbers of deactivated World War II bomb units. The new units adopted the insignia of their predecessors, adding missile symbols. The 490th Strategic Missile Squadron (left), a Minuteman II unit at Malmstrom AFB, Mont., descends from the 490th Bomb Squadron in World War II. The 400th SMS at F.E. Warren AFB, Wyo. (right), the only Peacekeeper unit in the Air Force, harks back to the 400th Bomb Squadron in World War II, and the unit today pays homage to its history by wearing the 90th Bomb Group “Black Pirates” insignia (far right) as its unofficial, “off-duty” patch. Not all missile units go quite that far back; the 91st Strategic Missile Wing (center), a Minuteman III wing at Minot AFB, N.D., was stated as a strategic reconnaissance wing and was activated in 1948.