United States aerial reconnaissance of the Soviet Union

Between 1946 and 1960, the United States Army Air Forces conducted aerial reconnaissance flights over the Soviet Union in order to determine the size, composition, and disposition of Soviet forces. Aircraft used included the Boeing B-47 Stratojet bomber and, from 1956, the Lockheed U-2 plane specifically designed for high-altitude reconnaissance. The program was ended following the U-2 incident of 1960.

Reconnaissance flights began in 1946 along the borders of the Soviet Union and other Socialist Bloc states. The necessity of peacetime overflights was reinforced after the escalation of the Cold War in the late 1940s and, in particular, after the Korea War started in 1950. US President Harry S. Truman authorized selected overflights of the Soviet Union in order to determine the status of its air forces. It was feared that the Soviets might launch a surprise aerial attack on the United States with long-range bombers.

In 1952 a modified B-47B bomber made the first deep-penetration U.S. overflight of Soviet territory to photograph Siberian air bases. Limited periphery flights had been conducted by US aircraft, including the Electronics intelligence RB-29, RB-50 and RB-47. Overflights of the Soviet Union with the newly designated RB-47Es started in 1954, often at great risk, as they were routinely intercepted by Soviet MiGs. It became apparent that a new aircraft was needed that could operate at altitudes well above any Soviet air defenses.

In November 1954, President Dwight D. Eisenhower approved a secret program under the direction of the CIA to build and fly a special-purpose high-altitude reconnaissance aircraft named Project AQUATONE. Lockheed was chosen to build the reconnaissance plane and in August 1955 the first Lockheed U-2 was test-flown.

...
Wikipedia