The End of the Bomber Gap
During the three-week period of 20 June to 10 July 1956, U-2’s had made eight overflights beyond the Iron Curtain, including five over the Soviet Union. PID’s photo interpreters were busy until the end of August with their initial evaluation of the photography obtained by these flights. Their efforts were complicated by the division’s move on 9 July from Que Building to the Stewart Building, but, when the photo interpreters were finished, they were able to write "finis" to the controversy over Soviet Bomber strength.
Although the Air Force had claimed that the Soviet Union possessed almost 100 of the new Myasishchev-4 (Bison) heavy bombers, U-2 photography proved this assertion wrong. There were no Bison bombers at any of the nine long-range bomber bases photographed by the July missions. DCI Allen Dulles was particularly impressed by the photographs of the Soviet bomber bases, which in later years he called "million-dollar" photography. The actual value of the U-2 photos was probably even greater because, on the strength of their evidence, the White House was able to deny Air Force requests for additional B-52 bombers to "catch up" to the Soviets.
Because of the need to protect the source of the information about Soviet bomber strength, the controversy surrounding this issue did not immediately die down. In November 1956, when the CIA began providing new Bison production figures based on U-2 photography without identifying the source, some members of Congress – unaware of the existence of the U-2 – questioned their motivation behind the reduced estimates. They suggested that either the earlier estimates of Soviet bomber strength had been inflated to increase Air Force appropriations or the new estimates had been reduced by White House direction in order to hold down military expenditures. No one in the White House, the CIA, or the Air Force could reveal that U-2 photographs had actually provided the primary evidence for the change in estimates.
To keep the existence of the U-2 program secret caused problems even within the CIA itself. The Office of Security sharply restricted the number of persons who could be cleared for access to U-2 photography. The special clearance was granted on a "slot" basis, and only the person assigned to a particular position or "slot" could have the clearance. The U-2 photographs were kept in a secure room, and only those with special clearances were admitted to the room. In addition, the Office of Security considered U-2 information too sensitive to use in CIA publications. As a result, many analysts did not have access to information that would have greatly aided the production of intelligence estimates.
