Multiple nations are holders of nuclear weapons, including the 5 permanent members of the UNSC.
The Israeli regime, is also possesor of nuclear weapons, though ti has not publicly admitted to it. But it is still very much two superpowers that control the majority of nuclear arms in the world, with Russia replacing the Soviet Union at the helm, and of course, the US maintaining their position as the worlds most armed nation, something that is causing UN Secretary General, Antonio Guterres much concern.