Changes

Four years after the first treaty, the two sides agreed to an Outer Space Treaty that prevented the deployment of nuclear weapons systems as satellites in space. Of far greater import, Soviet and U.S. negotiators also reached a settlement on concluding an international non-proliferation treaty.

By the beginning of the 1960s, nuclear weapons technology had the potential to become widespread. The science of exploding and fusing atoms had entered into public literature via academic journals, and nuclear technology was no longer pursued only by governments, but by private companies as well. Plutonium, the core of nuclear weapons, was becoming easier to obtain and cheaper to process.