This article makes the argument that the role of the European NATO (North Atlantic Treaty Organization) allies, and especially the non-nuclear weapon states (NNWS) under the Nuclear Nonproliferation Treaty (NPT), may and should play a key role in the future of nuclear disarmament. Once the Treaty on the Prohibition of Nuclear Weapons (TPNW) is signed and ratified by more or less 100 NNWS, mostly from the Global South, it will be up to the allied NNWS to make up their mind about their role vis-à-vis nuclear disarmament. Will they continue to behave as protégés by (and in some way also protectors of) the nuclear-armed states and break the disarmament process further, or will they shake off the nuclear “protection” in the interest of making progress toward a world without nuclear weapons? This article zooms in on the European NATO allies in particular. The TPNW can and will be used to put pressure on the European NATO allies to switch sides, and it can, on its turn, be used by the European NATO allies to stigmatize the nuclear-armed states in order to make progress in the direction of nuclear elimination. The article starts by reviewing the origins and objectives of the TPNW. In the next section, its impact will be scrutinized. We then turn to the current and possible future role of the European NATO allies.