jun 22, 1963 - 1963
June 20 - The U.S. and U.S.S.R. sign the 'hot line' agreement.
August 5 - Limited Test Ban Treaty signed by the U.S., U.S.S.R. and the U.K., prohibiting tests of nuclear devices in the atmosphere, in outer space, and underwater.
Added to timeline:
atomic and nuclear physics