Several U.S. allies participate in nuclear sharing through the North Atlantic Treaty Organization (NATO). According to publicly-available information, these countries are Belgium, Germany, Italy, the Netherlands, and Turkey. These countries occupy a special position in the nuclear world; they are classified as "non-nuclear" countries for the purposes of the Non-Proliferation Treaty (NPT), but they host nuclear weapons on their territory.
The Federation of American Scientists provides an overview of U.S. Nuclear Weapons in Europe.
The United States and NATO leadership continue to view this arrangement as crucial to the defense of Europe and the security of the free world, and make this case publicly, as in this recent op-ed in the Frankfurter Allgemeine, "Germany’s support for nuclear sharing is vital to protect peace and freedom."
This attitude, however, is not necessarily in line with domestic audiences, some of whom have long protested stationing weapons of mass destruction on their purportedly "non-nuclear" soil. Germany is a valuable example. Recent polls conducted by the Munich Security conference show that 66% percent of respondents said they believed Germany should “renounce nuclear deterrence entirely.” Polling by the International Campaign to Abolish Nuclear Weapons similarly shows that public opinion in EU states opposes nuclear weapons.
Public opinion has helped to drive the adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW). The treaty is widely understood to be symbolic, especially without the signatures of any nuclear power, but after collecting 50 signatures, the TPNW entered into force in January 2021. It is "the first treaty in history that categorically and permanently prohibits for all its parties the testing, possession, transfer, use, or threat of use of nuclear weapons, and that aims for universal participation" (source)
In the ICAN poll cited above, 68% of polled Germans believed the country should sign the TPNW. These developments, and the German Green Party's traditional opposition to all things nuclear, have led to an examination of the future of nuclear sharing given the upcoming German election.
Signature of the TPNW by any current nuclear-sharing state would likely significantly alter NATO deterrence policy, and would indicate a crack in the alliance. Thus, even if the TPNW has no "teeth," as critics point out, the outcome of this question has significant consequences for the future of transatlantic security environment.
This question asks whether any NATO member state currently hosting U.S. nuclear weapons will sign on to the Treaty on the Prohibition of Nuclear Weapons before 11:59pm on 31 December 2022.
Will a NATO nuclear-sharing country sign the TPNW by the end of 2022?
This question will resolve if any NATO member state hosting U.S. nuclear weapons as part of a "nuclear sharing" agreement as of 11 August 2021 signs on to the TPNW before the end of 2022.