What event occurred in May 1960 that damaged U.S.-Soviet relations?

The event that occurred in May 1960, which significantly damaged U.S.-Soviet relations, was the U-2 Incident. During this incident, an American U-2 spy plane was shot down over Soviet airspace. The pilot, Francis Gary Powers, was captured, and the U.S. government initially denied the purpose of the flight, claiming it was a weather research mission. However, when the Soviet Union produced the wreckage of the plane along with Powers as a prisoner, the U.S. was forced to acknowledge that it was conducting espionage.

This incident heightened tensions during the Cold War, as it was a blatant violation of Soviet sovereignty and showcased the risks of the espionage methods employed by both sides. The fallout from the U-2 Incident contributed to a deterioration in relations, leading to the collapse of a scheduled summit between U.S. President Dwight D. Eisenhower and Soviet Premier Nikita Khrushchev later that month, further escalating Cold War hostilities.