The U-2 Incident occurred in May of 1960, and was when a U.S. U-2 spy plane was shot down in Soviet airspace, and the pilot captured and imprisoned. This caused President Eisenhower to come forward and admitted that the CIA has been flying spy missions over the USSR for several years. The pilot that was captured had been sent to prison for 10 years on charges of committing espionage. This increased the already boiling tensions between the two nations because there was a planned meeting between Eisenhower and Russian leader Nikita Krushchev that was supposed to improve relations. I hope this helps :)