In 1956, the new U-2 reconnaissance aircraft entered service with the US Air Force. His creation was engaged in a secret division of the company Lockheed. The altitude of 20 km made the aircraft unreachable for the air defense of that time. But the CIA, in whose interests U-2 flew over enemy territory, was well aware that the sky of the Soviet Union would not be “open” forever. 1 May 1960, an American reconnaissance aircraft of this type was shot down over Sverdlovsk. Then the American leadership decided to stop U-2 flying over the territory of the USSR.
However, already at that time in America, work began on a more advanced reconnaissance aircraft project. The new machine, which was later called the Lockheed SR-71, was a real technical breakthrough.