During the 1950s, the new command began to make its mark. ARDC developed many ambitious aircraft and missile prototypes. Among the successes of this period were the North American F-86 Sabre swept wing fighter, the Boeing B-52 Stratofortress intercontinental bomber, the Boeing KC-135 Stratotanker jet-powered refueling tanker aircraft, the Lockheed C-130 Hercules turboprop transport and the Lockheed U-2 very high-altitude strategic reconnaissance aircraft. In addition, ARDC played a major contribution in the development of Intercontinental ballistic missiles (ICBMs), which became a priority after the world learned that the Soviet Union had detonated a thermonuclear (hydrogen) bomb on 23 August 1953. A crash program was employed which developed America's first ICBM (the SM-65D Atlas), that became operational in 1959. In terms of importance, resources, and success, the ICBM program was rivaled only by the famed Manhattan Project of World War II.