The Space Race was a 20th-century competition between two Cold War adversaries, the Soviet Union (USSR) and the United States (US), to achieve superior spaceflight capability. It had its origins in the ballistic missile-based nuclear arms race between the two nations following World War II. The technological advantage demonstrated by spaceflight achievements was seen as necessary for national security, and became part of the symbolism and ideology of the time. The Space Race enabled pioneering efforts to launch artificial satellites, uncrewed space probes to the Moon, Venus, and Mars, and human spaceflight in low Earth orbit and ultimately to the Moon.