At the end of the Second World War (1939-1945) the British and Americans discovered a mass of German aerial reconnaissance imagery, hidden by the Germans across multiple locations. Project TURBAN was the codename for the handling of all the material found. Much material came from Hitler's mountain retreat at Berchtesgaden in Bavaria, Germany, and was condenamed DICK TRACY. Other collections include material found in Vienna (codenamed ORWELL), Oslo (codenamed MONTHLY) and Berlin (codenamed TENANT).

In mid June 1945 the material was packaged in crates and flown to Britain. Upon its arrival at RAF Medmenham a UK-US exploitation project began. As the project developed, all the imagery became known as 'GX'. GX is such a large quantity of imagery that preliminary sorting work went on until 1949. The intelligence discovery provided mass aerial imagery of Eastern Europe and the Soviet Union on a scale unachievable at the time and remained a key intelligence resource for more than two decades. Even by 1960 much of the British and American target data consisted of predicted radar imagery of targets which were derived from the GX images.

Althought the British and Americans made a number of clandestine flights over the Soviet Union in the 1950s, the coverage obtained was small and GX was only replaced with the arrival of satellite reconnaissance imagery in the 1960s. The joint British-American project to exploit GX during the Cold War cemented the existing British-American air intelligence relationship that had been developed during the Second World War.