This open access volume surveys the state of the field to examine whether a fifth wave of deterrence theory is emerging. 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. 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. Contemporary conflict actors exploit a wider gamut of coercive instruments, which they apply across a wider range of domains. The prevalence of multi-domain coercion across but also beyond traditional dimensions of armed 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 Western and non-Western actors in order to assess how they hold up in today’s world. Air Commodore Professor Dr. Frans Osinga is the Chair of the War Studies Department of the Netherlands Defence Academy and the Special Chair in War Studies at the University Leiden. Dr. Tim Sweijs is the Director of Research at The Hague Centre for Strategic Studies and a Research Fellow at the Faculty of Military Sciences of the Netherlands Defence Academy in Breda.

Technology has been the spark that ignited NATO’s interest and commitment to scientific advancement during its history. Since its creation, the Science for Peace and Security (SPS) Programme has been instrumental to NATO’s commitment to innovation, science and technological advancement. During the years, SPS has demonstrated a flexible and versatile approach to practical scientific cooperation, and has promoted knowledge-sharing, building capacity, and projected stability outside NATO territory. The priorities addressed by the SPS Programme are aligned with NATO’s strategic objectives, and aim to tackle emerging security challenges that require dynamic adaptation for the prevention and mitigation of risks. By addressing priorities such as advanced technologies, hybrid threats, and counter-terrorism, the Programme deals with new, contemporary challenges. On 17-18 September 2019, the SPS Programme gathered at the KU Leuven University a wide number of researchers from a selection of on-going and recently closed SPS projects in the field of security-related advanced technologies for a “Cluster Workshop on Advanced Technologies”. The workshop covered, in particular, the following scientific domains: communication systems, advanced materials, sensors and detectors, and unmanned and autonomous systems. This book provides an overview on how these projects have contributed to the development of new technologies and innovative solutions and recommendations for future actions in the NATO SPS programme.

In this new Brookings Marshall Paper, Michael O'Hanlon argues that now is the time for Western nations to negotiate a new security architecture for neutral countries in eastern Europe to stabilize the region and reduce the risks of war with Russia. He believes NATO expansion has gone far enough. The core concept of this new security architecture would be one of permanent neutrality. The countries in question collectively make a broken-up arc, from Europe's far north to its south: Finland and Sweden; Ukraine, Moldova, and Belarus; Georgia, Armenia, and Azerbaijan; and finally Cyprus plus Serbia, as well as possibly several other Balkan states. Discussion on the new framework should begin within NATO, followed by deliberation with the neutral countries themselves, and then formal negotiations with Russia. The new security architecture would require that Russia, like NATO, commit to help uphold the security of Ukraine, Georgia, Moldova, and other states in the region. Russia would have to withdraw its troops from those countries in a verifiable manner; after that, corresponding sanctions on Russia would be lifted. The neutral countries would retain their rights to participate in multilateral security operations on a scale comparable to what has been the case in the past, including even those operations that might be led by NATO. They could think of and describe themselves as Western states (or anything else, for that matter). If the European Union and they so wished in the future, they could join the EU. They would have complete sovereignty and self-determination in every sense of the word. But NATO would decide not to invite them into the alliance as members. Ideally, these nations would endorse and promote this concept themselves as a more practical way to ensure their security than the current situation or any other plausible alternative.

"NATO has been a "nuclear" alliance since its inception. Nuclear weapons have served the dual purpose of being part of NATO military planning as well as being central to the Alliance's deterrence strategy. For over 4 decades, NATO allies sought to find conventional and nuclear forces, doctrines, and agreed strategies that linked the defense of Europe to that of the United States. Still, in light of the evolving security situation, the Alliance must now consider the role and future of tactical or non-strategic nuclear weapons (NSNWs). Two clear conclusions emerge from this analysis. First, in the more than 2 decades since the end of the Cold War, the problem itself -- that is, the question of what to do with weapons designed in a previous century for the possibility of a World War III against a military alliance that no longer exists -- is understudied, both inside and outside of government. Tactical weapons, although less awesome than their strategic siblings, carry significant security and political risks, and they have not received the attention that is commensurate to their importance. Second, it is clear that whatever the future of these arms, the status quo is unacceptable. It is past the time for NATO to make more resolute decisions, find a coherent strategy, and formulate more definite plans about its nuclear status. Consequently, decisions about the role of nuclear weapons within the Alliance and the associated supporting analysis are fundamental to the future identity of NATO. At the Lisbon Summit in Portugal in November 2010, the Alliance agreed to conduct the Deterrence and Defense Posture Review (DDPR). This effort is designed to answer these difficult questions prior to the upcoming NATO Summit in May 2012. The United States and its closest allies must define future threats and, in doing so, clarify NATO's identity, purpose, and corresponding force requirements. So far, NATO remains a "nuclear alliance," but it is increasingly hard to define what that means."--Publisher's website