This chapter analyzes NATO’s shifting role in cyber security since the late 1990s. Its core contention is that the past, present and future cyber security policy within the Alliance are inseparable—a continuum exists, which operates at a policy, ideational and cognitive level. The chapter draws on Quantum International Relations Theory (Der Derian/Wendt) highlighting how its key concepts, such as complexity, non-linearity, superposition, and entanglement, can illuminate the Alliance’s technological past, its present role in cyberspace and technological change, and its future. The chapter first outlines how developments in Quantum science, nuclear fusion and advances in algorithmic computing were integrally tied to the formation of NATO, and the emergence of a new security environment in which it emerged as a major actor. It then assesses the current state of NATO cyber policy and doctrine, including the issues that are most important in a quantum cyber context. The chapter then moves onto an analysis of NATO’s future role in cyber security, including the challenge of adapting to a range of new and emerging technologies. This last section explores why and how we need to rethink the role of alliances in digital spaces to prepare for an uncertain future.