This open access volume surveys the state of the field to examine whether a fifth wave of deterrence theory is emerging – both in the Western world but also outside of it – to address today's pressing strategic challenges. Ours is a period of considerable strategic turbulence, which in recent years has featured a renewed emphasis on nuclear weapons used in defence postures across different theatres; a dramatic growth in the scale of military cyber capabilities and the frequency with which these are used; and rapid technological progress including the proliferation of long-range strike and unmanned systems. These military-strategic developments occur in a polarized international system, where cooperation between leading powers on arms control regimes is breaking down, states widely make use of hybrid conflict strategies, and the number of internationalized intrastate proxy conflicts has quintupled over the past two decades. Globally, scholarly and strategic communities are updating, refining and further developing the analytical portfolio of deterrence concepts that take into account both actor-specific and domain-specific features to address these challenges. Bringing together insights from world-leading experts from three continents, the volume identifies the most pressing strategic challenges, frames theoretical concepts, and describes new strategies. The use and utility of deterrence in today’s strategic environment is a topic of paramount concern to scholars, strategists and policymakers. Because of a combination of military-strategic, technological, and socio-political developments, contemporary conflict actors exploit a wider gamut of coercive instruments, which they apply across a wider range of domains for strategic gain. These encompass both nuclear and conventional military instruments, but also include non-military instruments of state power deployed in grey-zone conflicts under the threshold of military violence. The prevalence of multi-domain coercion across but also beyond traditional dimensions of conflict raises an important question: what does effective deterrence look like in the 21st century? Answering that question requires a re-appraisal of key theoretical concepts and dominant strategies of the deterrence literature in order to assess how they hold up in today’s world. Air Commodore Professor Frans Osinga is the special chair in War Studies and Professor of War Studies at the University Leiden. Dr. Tim Sweijs is a research fellow at the Faculty of Military Sciences of the Netherlands Defence Academy in Breda, The Netherlands weiterlesen