The best offence is a good defence? : The effects of ballistic missile defence on nuclear deterrence

Despite a significant amount of research addressing the effects of Ballistic Missile Defence (BMD) on nuclear deterrence, little consensus exists as to how BMD specifically affects the strategic calculus of great power nuclear deterrence. Nor is there consensus as to why great powers would seek to destabilise the offence-offence balance that has dominated great power relations during and after the Cold War. This study tests whether a theoretical framework of offensive realism, in combination with deterrence theory and offence-defence theory, can provide a compelling argument as to why great powers would seek to deploy BMD, and what steps affected rival great powers would take to address the resulting strategic imbalance. To do this, the thesis presents two case studies, assessing US BMD deployments in Europe and the Asia-Pacific, the claimed purpose of these deployments (the defence against the 'rogue' states Iran and North Korea respectively) and whether these deployments are actually oriented towards providing defence against Russia and China. By analysing the US BMD deployments, and the subsequent responses Russia and China are taking to address or circumvent the threat posed by US BMD, the thesis presents the argument that offensive realism provides a credible and authoritative explanation for both the US motivations for deploying BMD, namely increasing its relative power, and moving closer to achieving nuclear superiority over its rivals. Further, the study found that the effects of BMD on great powers are not homogenous, and do not have a single effect ‚Äö- Rather, the impacts vary due to the existing nuclear relationship between Russia and the US on the one hand, and the US and China on the other. The result of this difference is that Russia and China are responding in different ways, and that Russia, due to its reliance on its nuclear deterrent and tactical nuclear weapons, is suffering more adverse effects than China, which does not rely as heavily on its nuclear deterrent for its overall security. Additionally, the study finds that current BMD capabilities are irrelevant, and that it is the perception of potential future capability that are causing Russia and China to respond to US BMD in order to maintain the credibility of their respective nuclear deterrents.