Lockheed U-2
The United States wanted to keep the purpose of the U-2 secret, but on May 1, 1960, Francis Gary Powers was shot down in his U-2 by a Soviet SAM SA-2 missile. In 1962, Powers was released and traded for captured Soviet spy Rudolf Abel. After this, the SR-71 Blackbird started spying on the Soviet Union, which was faster and harder to see on radar.