Penetrating the Iron Curtain

"In the mid-1950s the US faced the first real challenge since World War II to its strategic superiority over any nation on earth. The attempt to collect intelligence on the Soviets began with an initial period of poor collection capabilities and consequent limited analysis. With few well-placed human sources inside the Soviet Union, it was only with the CIA's development of, what can only be called, timely technological wizardry--the U-2 aircraft and Corona Satellite reconnaissance program--that breakthroughs occurred in gaining valuable, game-changing intelligence. Coupled with the innovative use of aerial and satellite photography and other technical collection programs, the efforts began to produce solid, national intelligence."--https://www.cia.gov/library/publications/historical-collection-publications/index.html