Nuclear sharing is a concept in deterrence theory in which a nuclear-armed country deploys nuclear weapons on the territory of a country that does not possess nuclear weapons and extended its nuclear deterrent to that country. Nuclear sharing typically also involves joint planning and training processes for potentially using them, going beyond nuclear stationing or nuclear basing, which refer to a nuclear-armed country's deployment of nuclear weapons on foreign soil without an operational role for the host country's military and government.
It was originally conceived during the Cold War, when the United States and the Soviet Union placed their own nuclear weapons in many non-nuclear countries of the American-aligned First World and the Soviet-aligned Second World, as part of the nuclear arms race between the two sides. However, since the dissolution of the Soviet Union in 1991, the concept continues to be practiced by the United States and Russia. United States nuclear weapons, for delivery by fighter aircraft, are based in Belgium, Germany, Italy, the Netherlands, Turkey, and the United Kingdom. Russian nuclear weapons, for delivery by aircraft and short-range missiles, are deployed in Belarus.