Soviet Protest Note
The 4 and 5 July overflights brought a strong protest from the Soviet Union on 10 July in the form of a note handed to the US Embassy in Moscow. The note said that the overflights had been made by a "twin-engine medium bomber of the United States Air Force" and gave details of the routes flown by the first two missions. The note did not mention Moscow or Leningrad, however, because the Soviets had not been able to track these portions of the overflights. The Soviet note stated that the flights could only be evaluated as "intentional and conducted for the purpose of intelligence". As soon as the note arrived at the White House on the evening of 10 July 1956, Colonel Goodpaster called Richard Bissell and told him to stop all U-2 overflights until further notice. The next morning Goodpastor met with Bissell to review the U-2 situation. Bissell said three additional flights had taken place since the missions mentioned in the Soviet note but added that no more were planned.
Later Eisenhower told Goodpastor that he "didn’t like a thing" about the Soviet note and was going to discuss the matter with Secretary of State Dulles. With the strong approval of President Eisenhower, Goodpastor informed DCI Dulles that "there is to be no mention of the existence of this project or of operations incident to it, outside of the Executive Branch, and no mention within the Executive Branch to others other than those who directly need to know of the operation, as distinguished from output deriving from it".
During these initial overflights, the U-2 flew above 69,000 feet and could be seen only fleetingly by pilots of the Soviet interceptor aircraft. Thus, it appears that the Soviet claim that the intruder was a twin-engine bomber was probably based on the assumption that this was another overflight by a reconnaissance version of the twin-engine Canberra bomber, similar to the RAF overflight of Kapustin Yar in 1953. The US reply sent to the Soviets on 19 July, truthfully denied that any US "military planes" had overflown the Soviet Union on the days in question. Meanwhile, on 16 July the Polish Ambassador to the United States delivered an oral protest concerning overflights of Poland on 20 June and 2 July. This was followed by a protest note from the Czechoslovakia Government on 21 July. No formal reply was sent to the two Soviet satellite states.
The details of the flight paths listed in the Soviet and Polish protests, along with the subsequent photographic evidence of Soviet interception attempts, made it clear that U-2s could not fly undetected over the Soviet Union or Eastern Europe and could even be tracked for extended periods of time. This news greatly disturbed President Eisenhower. In a meeting with Allen Dulles on 19 July 1956, the President recalled how he had been told that "not over a very minor percentage of these (flights) would be picked up". He went on to question "how far this should now be pushed, knowing that detection is not likely to be avoided". After discussing the possibility of basing U-2s in the Far East, President Eisenhower went on to say that he had "lost enthusiasm" for the U-2 activity. He noted that, if the United States were on the receiving end of a Soviet overflight operation, "the reaction would be drastic". The President was also concerned that the American public might learn of the overflights and be shocked that their country had violated international law. He stated, "Soviet protests were one thing, and loss of confidence by our own people would be quite another".
The President’s rapid disenchantment with the project was not lost on Richard Bissell. Fearing for the U-2 program’s survival, he met with the Land committee in early August 1956 to urge them to help make the U-2 less vulnerable to radar pulses. His goal was to reduce the aircraft’s radar cross section so that it would be less susceptible to detection. Edward Purcell had some ideas on this and suggested that he supervise a new project in the Boston area to explore them. At the direction of the Land committee, Bissell set in motion a new project which would have many MIT scholars who had conducted studies and experiments into radar-absorbing materials and techniques proposed by Purcell. The effort, known as Project Rainbow, got under way by the end of the year.
