Ukraine ousted Khrushchev and became the Soviet leader from 1964 to 1982. Many prominent Soviet sports players, scientists, and artists came from Ukraine. On 26 April 1986, a reactor in the Chernobyl Nuclear Power Plant exploded, resulting in the Chernobyl disaster, the worst nuclear reactor accident in history. This was the only accident to receive the highest possible rating of 7 by the International Nuclear Event Scale, indicating a "major accident", until the Fukushima Daiichi nuclear disaster in March 2011. At the time of the accident, 7 million people lived in the contaminated territories, including 2.2 million in Ukraine. After the
Nuclear weapons and Ukraine of Independent States. In 1994 Ukraine agreed to destroy the weapons, and to join the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). As a republic in the Soviet Union, Ukraine was the base for the following nuclear forces: International relations theorist John Mearsheimer predicted a Ukraine without any nuclear deterrent was likely to be subjected to aggression by Russia, but this was very much a minority view at the time. A 2016 study argues that the denuclearization of Ukraine was not a "stupid mistake" and that it is unclear that Ukraine would be better off as a nuclear state.