While it's true nuclear proliferation began with the five permanent members, at the time the UN and Security Council were founded in 1945, only the US had the b

While it's true nuclear proliferation began with the five permanent members, at the time the UN and Security Council were founded in 1945, only the US had the bomb. The USSR didn't test one until 1949, the UK in 1952, France in 1960, and China (as you mentioned) in 1964. The Soviet Union had an early start because of their spies in the Manhattan Project, while the UK contributed to it during the War. 15 years would pass before another permanent member caught up. And Russia took the USSR's seat just as China did Taiwan's.