The successful conclusion of the Treaty on the Prohibition of Nuclear Weapons (TPNW) has challenged the global nuclear order, but was dependent on bypassing the nuclear weapon states (NWS) and their allies. This has led critics to dismiss its practical value for nuclear disarmament. Proponents of the ban treaty, however, hope for a “transformative political dynamic” that delegitimizes nuclear weapons and leads to NWS and their allies joining the TPNW. This article contributes both conceptually and empirically to the discussion of this “transformative political dynamic”. It deals with the role of nuclear weapons for NATO membership and the strategies for legitimizing and delegitimizing nuclear weapons. The case study on Belgium analyzes the processes of coalition building and the discursive strategies related to Belgium’s nuclear role in NATO. The study shows that the exchange of symbolic arms control and disarmament initiatives for the approval of military budgets and the acquiescence to the claimed nuclear obligations of NATO membership stands on shaky ground.