NEW TECHNOLOGIES AND NUCLEAR DISARMAMENT Outlining a Way Forward tytti erästö STOCKHOLM INTERNATIONAL PEACE RESEARCH INSTITUTE SIPRI is an independent international institute dedicated to research into conflict, armaments, arms control and disarmament. Established in 1966, SIPRI provides data, analysis and recommendations, based on open sources, to policymakers, researchers, media and the interested public. The Governing Board is not responsible for the views expressed in the publications of the Institute. GOVERNING BOARD Ambassador Jan Eliasson, Chair (Sweden) Dr Vladimir Baranovsky (Russia) Ambassador Chan Heng Chee (Singapore) Espen Barth Eide (Norway) Jean-Marie Guéhenno (France) Dr Radha Kumar (India) Ambassador Ramtane Lamamra (Algeria) Dr Patricia Lewis (Ireland/United Kingdom) Dr Jessica Tuchman Mathews (United States) Dr Feodor Voitolovsky (Russia) DIRECTOR Dan Smith (United Kingdom) hiroshima prefecture NEW TECHNOLOGIES AND NUCLEAR DISARMAMENT Outlining a Way Forward tytti erästö May 2021 Contents Acknowledgements iv Summary v Abbreviations vi 1. Introduction 1 2. The nuclear deterrence paradigm: An enduring challenge to 3 disarmament I. ‘Transitional’ approach: Bridging the gap between deterrence and disarmament 3 II. Minimal deterrence: An interim step towards a nuclear weapon-free world 4 III. Increasing reliance on conventional deterrence 6 IV. The need for a more cooperative international society 8 3. New technologies and prospects for minimal nuclear deterrence in 10 Russia and the United States I. Conventional precision-strike: Alternative to nuclear weapons? 10 II. Missile defences: Obstacle to further cuts in strategic nuclear arsenals? 14 Box 3.1. The link between missile defence and nuclear arms control 15 Box 3.2. Non-kinetic weapons 16 4. The path to global zero 18 I. Strategic challenges to multilateral nuclear disarmament 18 II. The role of technology in maintaining a nuclear weapon-free world 20 5. Policy recommendations 21 6. Conclusions 24 Acknowledgements The author would like to thank the Hiroshima Prefectural Government for its generous funding of this paper. She is also indebted to several reviewers who provided valuable feedback on the report: external reviewers Professor Andrew Futter and Dmitry Stefanovich, as well as SIPRI colleagues, including Dr Ian Anthony, Dr Sibylle Bauer, Dr Lora Saalman, Dan Smith, Dr Petr Topychkanov, Pieter D. Wezeman and Robert E. Kelley. Dr Tytti Erästö Summary This report analyses the prospects for nuclear disarmament in light of recent military- technological advances, focusing on precision-strike weapons and missile defences. While many of the technologies employed in these advanced weapon systems cannot be described as new, their application to strategic military uses represents a more recent development whose impact on nuclear deterrence and, in particular, nuclear disarmament remains poorly understood. The report argues that the tension between deterrence and disarmament can be bridged through a ‘transitional approach’ which acknowledges both the urgent need for progress towards a nuclear weapon-free world and the security-related challenges in its way. It views the resumption of bilateral arms control between Russia and the United States as the most important step towards disarmament at the present moment, as a broader process involving all nuclear-armed states is hardly possible with out prior and significant reductions in the largest nuclear weapon arsenals. To enable such reductions, these two countries should move away from their cold-war era nuclear doctrines that seek an ability to win a nuclear war. Instead, they should pursue a policy of ‘minimal nuclear deterrence’ focused on deterring a nuclear attack. If these two countries were to adopt such a policy—and, ideally, also make a nuclear no-first-use (NFU) pledge—this would constitute a crucial intermediate goal towards comprehensive nuclear disarmament. Although disarmament ultimately means giving up nuclear deterrence, the inter- mediate goal of minimal nuclear deterrence would not require consensus on the feasibility of the end goal of nuclear abolition. Instead, the shared goal of nuclear risk reduction might be a sufficient motivation for Russia and the USA to embark on significant nuclear weapon reductions. They could begin such cuts by removing nuclear weapons from regional conflict dynamics, meaning that they would no longer serve as a deterrent against con- ventional aggression. Such a change—which could involve a ban on non-strategic nuclear weapons in Europe—would not undermine regional deterrence. This move, the report argues, would not undermine regional deterrence, as each side already has robust conventional forces comprised of precision-strike weapons and other advanced mili tary systems. Together with the abandonment of cold war-era nuclear doctrines focused on extensive counter-force targeting, this would open the door for signifi cant reductions of nuclear stockpiles. Such progress, however, would be complicated by current challenges to strategic stability posed by US missile defences and long-range precision-strike weapons, notably hypersonic weapons. These systems have raised the bar for credible nuclear deterrence by creating uncertainty about US adversaries’ second-strike capabilities. To address this problem, the report proposes treaty-based limits on strategic missile defences and strengthened international norms against both nuclear and con ventional aggres sion, in particular against preventive war. Together with a clear stigma against nuclear weapons, such measures could also pave the way for the kind of systemic change that is required for further progress towards a nuclear weapon-free world. Abbreviations ABM Treaty 1972 Anti-Ballistic Missile Treaty ASAT anti-satellite C3 command, control and communications CPGS Conventional Prompt Global Strike GBI ground-based interceptor ICBM intercontinental ballistic missile INF Treaty 1987 Intermediate Range Nuclear Forces Treaty MDR Missile Defense Review NATO North Atlantic Treaty Organization New START 2010 Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms NFU no first use NPR Nuclear Posture Review NPT 1968 Treaty on the Non-Proliferation of Nuclear Weapons RMA Revolution in Military Affairs SALT Strategic Arms Limitations Talks SDI Strategic Defense Initiative SLBM submarine-launched ballistic missile START I 1991 Treaty on the Reduction and Limitation of Strategic Offensive Arms TPNW 2017 Treaty on the Prohibition of Nuclear Weapons WMD weapons of mass destruction 1. Introduction Much of the current analysis on the impact of ongoing technological evolution on nuclear deterrence is driven by concerns about strategic stability. Reflecting the view that this impact is predominantly negative, the attribute ‘disruptive’ is often used to refer to new kinds of destabilizing weapons, or to technologies that poten tially enable their development.1 While specific weapons types are sometimes iden tified as representing new technologies, the issue is perhaps best understood in terms of a general trend towards greater precision, speed, manoeuvrability, stealth and tracking capabil ities of contemporary military systems, as well as non-kinetic means of attack, notably in the cyber realm.2 This trend poses a challenge to strategic stability.3 More specifically, new technologies may create ‘crisis instability’ through their potential to increase the risk of nuclear escalation, for example through miscalculation and the entanglement of nuclear and conventional weapons.4 A related problem is that—insofar as they are able to destroy hardened and concealed targets—modern conventional systems could be used to forcefully disarm an adversary.5 Together with improvements in strategic defences that could neutralize the effects of retaliatory strikes, these emerging capabil- ities are weakening deterrence by undermining nuclear-armed states’ confidence in their ability to launch a retaliatory second strike.6 By driving nuclear-armed states to engage in new armament dynamics to preserve their second-strike capability, new tech nologies are thus also undermining ‘arms race stability’: the other key pillar of strategic stability. Focusing in particular on the latter aspect of strategic stability, this report analyses the pitfalls and possibilities that such weakening of deterrence presents for nuclear dis- armament. On the one hand, it starts from the assumption that the arms race instability created by new technologies will likely complicate efforts to cut nuclear weapon stockpiles. Illustrative of the pitfalls, China and Russia have already responded to the emerging United States’ strategic capabilities by reinforcing their nuclear arsenals in an effort to maintain mutual deterrence. On the other hand, the report considers the possi bilities for harnessing the current military-technological evolution to facilitate dis armament, notably by exploring the idea of substi tuting nuclear deterrence with conventional deterrence. 1 Roberts, B., ‘Emerging and disruptive technologies, multi-domain complexity, and strategic stability: A review and assessment of the literature’, Lawrence Livermore National Laboratory, Center for Global Security Research, Feb. 2021. 2 Futter, A., ‘The risks posed by emerging technologies to nuclear deterrence’, eds B. Unal, Y. Afina and P. Lewis, Perspectives on nuclear deterrence in the 21st century, Chatham House Research Paper (Royal Institute of International Affairs: London, Apr.