The Validity of Deterrence in the Twenty-First Century

Deterrence is one of those ‘accepted’ doctrines used by governments worldwide for defence and security. Yet while some states continue to execute and rely on the concept as a cornerstone of national-security policy, recent Western experience has called into question the validity of the doctrine as a broad approach within the security environment of the twenty-first century.

Policy-level discussion in Europe on the subject has not markedly changed since the 1970s, but scholars have continued to research and publish on deterrence – not just in terms of nuclear or strategic weapons but also through examining the concept in relation to rogue states, terrorist actors and cyber-domains. This report draws together these discussions, examining debates over escalation dominance, as well as quantitative, horizontal and vertical leverage, in deterrence. The paper also baselines knowledge on the theories of deterrence and suasion from their original authors and applies them to practical, recent examples of deterrence around the world.

The authors find that deterrence remains a valid concept for a new security environment provided that certain facets are considered, the primary one being understanding deterrence from an adversary’s rather than from one’s own perspective. The report additionally draws some conclusions for the future about how to consider and apply deterrence doctrines in ‘new’ areas of conflict.

About the Authors

Peter Roberts is a Senior Research Fellow for Sea Power and Maritime Studies at RUSI.

Andrew Hardie is a visiting fellow at RUSI.