American Military History, Volume 2 by Richard W. Stewart

The aftermath of the crises in Berlin and Cuba produced sev- eral unexpected developments. Apparently convinced that further confrontations might be unwise, the Soviet Union adopted a more conciliatory attitude in its propaganda and suggested that at long last it might be willing to conclude a nuclear test ban treaty. Under the provisions of the accord that followed in the fall of 1963, the So- viet Union, the United Kingdom, and the United States agreed to refrain from conducting nuclear test explosions underwater, in the atmosphere, or in space. Only underground explosions would be per- missible, but no radioactive material from such tests was ever to reach the surface. Although France weakened the treaty by declining to ei- ther ratify or adhere to it, the pact still marked a major breakthrough in what had been a long history of fruitless negotiation over nuclear weapons.

One possible explanation for the Soviet willingness to cooperate with the West in the sixties may have been the growing independence of Communist China. The Chinese had never embraced the idea of peace- ful coexistence with Capitalist countries and had criticized Moscow as too soft on the West. As the Sino-Soviet rift had widened, the Soviet Union seemed to adopt a less threatening stance in Europe, although no direct correlation could be proven.