As nuclear weapons are again becoming the subject of critical scholarship and progressive activism, this article seeks to widen the perspective of critical security studies in relation to nuclear weapons and to provide a better understanding of the historical precursors of current ambitions. We do so by focusing on the central decade of the thermonuclear revolution (ca 1952–1963) and on a body of thought we term ‘nuclear realism’. Nuclear realists were united by the central conviction that liberal modernity could survive collective suicide only by radically rethinking and transforming its foundations. Günther Anders, John Herz, Lewis Mumford and Bertrand Russell take centre stage, and we highlight that the central pillars in their project of nuclear critique was a dissection of the legacy of the Enlightenment and an incisive examination of its implications for (international) politics in the nuclear age. These dimensions came together in their critique of the prevailing concept of deterrence. In an attempt to reclaim nuclear politics for a wider public, nuclear realists stressed the absolute centrality of imagination as a strategy for unmasking the power and rationality of a growing national security establishment, on the one hand, and bringing a distinct, alternative vision of global politics and security into view, on the other. This comprehensive yet multifaceted project, while afflicted by its own challenges, is deeply relevant for today’s nuclear politics.