Nuclear disarmament is firmly back on the international agenda. But almost all current thinking on the subject is focused on the process of reducing the number of weapons from thousands to hundreds. This rigorous analysis examines the challenges that exist to abolishing nuclear weapons completely, and suggests what can be done now to start overcoming them.

The paper argues that the difficulties of 'getting to zero' must not preclude many steps being taken in that direction. It thus begins by examining steps that nuclear-armed states could take in cooperation with others to move...