On May 1, 1960, a United States U-2 spy plane was shot down in the airspace of the Soviet Union. The incident happened fifteen days before the scheduled opening of an East–West summit conference in Paris.
On Dec. 25, 1991, Mikhail Gorbachev resigned as president of the Soviet Union. The next day, the Supreme Soviet of the Soviet Union meets and formally dissolves the Union of Soviet Socialist Republics.