The U.S. Navy had been tasked with building a rocket to lift satellites into orbit, but the resulting Vanguard rocket launch system was unreliable. In 1957, with the launch of Sputnik 1, a growing belief within the United States existed that it was lagging behind the Soviet Union in the emerging Space Race. American authorities then chose to use von Braun and his German team's experience with missiles to create an orbital launch vehicle. Von Braun had originally proposed such an idea in 1954, but it was denied at the time.