Our first case of nuclear weapons represents one that is predominantly state-centric, and is centred on core issues of international security. If there is one domain that approximates the Waltzian view of great powers taking on special responsibilities, this should be it: material capability and role converge to the point where there is no space left for any social idea of responsibility at all. In fact, as we will show, the nuclear domain has not simply followed this Waltzian dictum.

This chapter examines the nature and functioning of special responsibilities in relation to the development and possession of nuclear weapons, and it centres on an examination of the 1970 Nuclear Non-Proliferation Treaty (NPT). The reason for focusing on the NPT is that it established a legal categorisation between those that were recognised as nuclear weapon states (NWSs) and those non-nuclear weapon states (NNWSs) that consented, whilst parties to the treaty, to give up the right to acquire nuclear weapons. For our purposes, it is crucial that this categorisation became the focus of expectations (which pre-dated the treaty) regarding the special responsibilities of the nuclear and non-nuclear powers. We show how these special responsibilities have mediated between the principle of sovereign equality, on the one hand, and the stubborn fact of material inequality, on the other. Moreover, and contrary to the Waltzian argument, the chapter demonstrates how these special responsibilities constitute the possibilities of legitimate political action within this domain, supporting our cardinal claim in the book that special responsibilities cannot just be unilaterally asserted by powerful states, but have to be recognised as such by those to whom they are addressed.