This chapter proposes a reinterpretation of the origins of the acrimonious nuclear debate among North Atlantic Treaty Organisation (NATO) countries in the 1980s. It argues that renewed interest in one face of the atom – nuclear energy – elicited by the rise of modern environmentalism, rejuvenated interest and concern in the other more destructive face – nuclear weapons. The chapter then proposes to look at the nuclear debate of the 1980s as part of a larger ideological struggle between two "nuclear ideas" that emerged from the counterculture of the 1970s. First one claiming that the Soviet Union was getting ahead and thereby the West needed more nuclear weapons. Another one claiming that more nuclear weapons would only hasten the arms race in a spiral leading to nuclear war. This fracture undermined one of the most tacit and fundamental consensuses on which the Cold War order resided: the acceptance of nuclear deterrence as the foundation of Western security.