Royal Navy Vanguard Class submarine HMS Vigilant returning to HMNB Clyde after extended deployment. The four Vanguard-class submarines form the UK's strategic nuclear deterrent force. Photo: Ministry of Defence.
Royal Navy Vanguard Class submarine HMS Vigilant returning to HMNB Clyde after extended deployment. The four Vanguard-class submarines form the UK's strategic nuclear deterrent force. Photo: Ministry of Defence.

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Summary

  • This collection of essays explores, from the perspectives of eight experts, four areas of deterrence theory and policymaking: the underlying assumptions that shape deterrence practice; the enduring value of extended deterrence; the impact of emerging technologies; and the ‘blurring’ of the lines between conventional and nuclear weapons.
  • Nuclear deterrence theory, with its roots in the Cold War era, may not account for all eventualities in security and defence in the 21st century, given the larger number of nuclear actors in a less binary geopolitical context. It is clear that a number of present factors challenge the overall credibility of ‘classical’ nuclear deterrence, meaning that in-depth analysis is now needed.
  • Uncertainty as to the appetite to maintain the current nuclear weapons policy architecture looms large in discussions and concerns on global and regional security. The demise of the Intermediate-Range Nuclear Forces Treaty, doubts over the potential extension of the New Strategic Arms Reduction Treaty, heightened regional tensions in Northeast and South Asia, together with the current and likely future risks and challenges arising from global technological competition, making it all the more urgent to examine long-held assumptions in the real-world context.
  • Extended deterrence practices differ from region to region, depending on the domestic and regional landscape. Increased focus on diplomatic capabilities to reduce risks and improve the long-term outlook at regional level, including by spearheading new regional arms-control initiatives, may be a viable way forward. Addressing the bigger picture – notably including, on the Korean peninsula, Pyongyang’s own threat perception – and the links between conventional and nuclear missile issues will need to remain prominent if long-term and concrete changes are to take hold.
  • Most states have long held nuclear weapons to be ‘exceptional’: their use would represent a dramatic escalation of a conflict that must never be attained. Latterly, however, some officials and scholars have made the case that the impact of the use of a low-yield nuclear weapon would not be entirely distinct from that of a large-scale conventional attack. This blurring of lines between conventional and nuclear deterrence strips nuclear weapons of their exceptional nature, in a context in which states are faced with diverse, complex and concurrent threats from multiple potential adversaries that are able to synchronize non-military and military options, up to and including nuclear forces. The use of nuclear weapons risks becoming a ‘new normal’, potentially reducing the threshold for use – to cyberattacks, for example. This has direct implications for discussions around strategic stability.
  • While emerging technologies may offer tremendous opportunities in the modernization of nuclear weapons, they also present major risks and destabilizing challenges. Artificial intelligence, automation, and other developments in the cyber sphere affect dynamics on both the demand and supply sides of the nuclear deterrence equation. States and alliance such as NATO must adapt their deterrence thinking in light of these technological developments, and define their primary purpose and priorities in this shifting security context. Resilience planning, adaptation to the evolving security environment, threat anticipation, and consistent crisis management and incident response – as well as thinking about the mitigation measures necessary to prevent conflict escalation should deterrence fail – will all be critical in upholding nuclear deterrence as both policy and practice.