No.No. 116 [ ] October[Date] 2019 Articulating the logic of nuclear-sharing Alexander Mattelaer weapons exist. By extension, it underwrites the NATO’s nuclear-sharing arrangements collective security of its members, which is based often get bad press. This is remarkable on a strategy of deterrence and defence. As given the fact that they have demonstrably nuclear-sharing makes for a politically sensitive contributed to (a) countering the subject, public discussion thereof has often proliferation of nuclear arsenals in Europe, remained muted. This has resulted in a widening (b) fostering alliance cohesion by giving gap between what is official policy and the public non-nuclear weapon states a voice on the understanding thereof. Yet sustaining leadership nuclear posture of the alliance, and (c) focus is premised on informing and educating the making nuclear deterrence more effective next generation of leaders with consideration and militarily by offering a wider array of force deliberation.1 In this sense, the desire to avoid options. When the relative merits of difficult debates with critical publics constitutes extended nuclear deterrence are perhaps the gravest risk to NATO’s deterrence unknown, public support thereof is likely posture today. to suffer. In order to enrich the debate about NATO’s nuclear policy, this The logic of nuclear-sharing revolves around three functions subsumed within the wider Security Policy Brief articulates the framework of NATO’s nuclear policy. First threefold logic of nuclear-sharing. comes the non-proliferation function: nuclear- sharing helps maintaining strategic stability by limiting the number of nuclear arsenals in INTRODUCTION Europe. Second comes the political cohesion Nuclear-sharing plays a critical, though little- function: nuclear-sharing ensures that the understood role in the nuclear posture of the benefits, responsibilities and risks that derive NATO alliance. The forward deployment of US from NATO’s nuclear posture are shared across nuclear weapons in Europe, enabled by delivery different allies. As such it also provides different systems and infrastructure provided by different allies with a voice on nuclear matters that they allies, helps cementing the notion that NATO would otherwise lack. Third comes the military will remain a nuclear alliance as long as nuclear flexibility function: nuclear-sharing enhances the EGMONT Royal Institute for International Relations #1 strategic effectiveness of nuclear deterrence by The sharing of nuclear weapons was originally offering a wider and more credible array of force conceived as a way to limit the proliferation of options. Of course, NATO’s nuclear posture European nuclear arsenals.2 Already in 1952, the relies foremost on the triad of US strategic forces, UK became the second Western nation achieving as well as on the strategic forces of France and nuclear weapon status. Subsequently, under the the United Kingdom. Not only do these forces leadership of president Charles de Gaulle, and provide NATO with the means to impose following the loss of confidence in US assistance unacceptable costs on any adversary, they also due to the way the Suez crisis unfolded, France ensure the ultimate survivability of NATO’s own also embarked on a nuclear weapons programme. arsenal, especially by continuous at sea deterrence It detonated its first device in 1960 and chose to and by the quasi-bottomless ‘missile sink’ leave NATO’s military command structure in provided by the intercontinental ballistic missile 1966. Ever since it has prided itself on its relative force of the US. Yet in today’s environment, in ‘strategic autonomy’, of which the force de frappe which the arms control architecture is eroding, constitutes the very foundation.3 The accession and Russian nuclear sabre-rattling has made an of West Germany to NATO in 1955 and the unwelcome comeback, the different functions fraught debate over (West-)German rearmament performed by NATO’s nuclear-sharing brought about intensifying reflection on how to arrangement are increasing in salience. This curtail the need for NATO allies to Egmont Security Policy Brief sets out to autonomously provide for their own nuclear illuminate these three functions throughout the capabilities. The idea of multilateralising the past, present and potential future timeframes. ownership and control of nuclear weapons under US leadership logically came to fill the void. THE HISTORICAL CONCEPTION OF NATO’s nuclear-sharing arrangements were fully NUCLEAR-SHARING integrated into the negotiations leading up to the In today’s debates about European security it is Non-Proliferation Treaty.4 often forgotten that nuclear-sharing originated in a very different historical context. The late 1950s The stationing of US nuclear weapons on the and early 1960s constituted a timeframe when the territory of its European allies, followed by the nuclear deterrence architecture was up for grabs, inclusion of delivery systems owned by allies and and different European allies contemplated the dual-key control mechanisms also served a development of nuclear weapons. Nuclear- political purpose in strengthening the credibility sharing came into existence primarily as a of extended deterrence. The Gaullist argument mechanism to avoid the proliferation of nuclear for developing an independent arsenal was weapons. In addition, allies gradually came to premised on doubts whether the US would risk appreciate the political and military advantages the destruction of its own cities on behalf of the that nuclear-sharing conferred, most notably by defence of its allies. Yet by hosting US nuclear bolstering the credibility of the US nuclear weapons and by acquiring the means to operate umbrella. Also, it provided allied militaries with and deliver these, the promise of extended the needed sense of co-ownership of nuclear deterrence became materially tangible. While capability and risk, in combination with remaining under US control, the allies concerned continuous diplomatic consultations for acquired a palpable degree of influence on how exercising political control. the nuclear posture of the alliance would evolve over time. The creation of the Nuclear Planning EGMONT Royal Institute for International Relations 2 #1 Group in 1966, in parallel to the drafting of the in declaratory posture codified in the NATO Harmel Report, proved instrumental in this summit communiqués from 2014 to 2018 regard: it provided those allies hosting US nuclear constitutes ample evident thereof. weapons with special influence on nuclear planning and release authority.5 Perhaps equally noteworthy is the fact that the non-proliferation function of nuclear-sharing, The involvement of European allies in matters of which largely disappeared from view, is beginning nuclear strategy also acquired military to make a comeback. The critical attitude significance. The rapid growth of both US and President Trump has espoused towards the Soviet arsenals in terms of the number of NATO alliance has fuelled European concerns weapons and delivery systems paved the way for about the credibility of the US extended an escalation ladder starting with battlefield use deterrence commitment. While European leaders of nuclear munitions and potentially leading to a such as German Chancellor Angela Merkel and full-blown exchange between US and Soviet French President Emmanuel Macron have only intercontinental ballistic missile forces. European noted the need to assume more responsibility for allies and West Germany in particular developed European security, others have already gone an appreciation for keeping the escalation ladder further by advocating a French-led European short and steep. Their aim was to avoid becoming deterrent or even the development of an a nuclear battlefield on which the two independent German nuclear arsenal.6 While superpowers could settle their differences such proposals may fail to gain endorsement for without risking their own territory. Yet the a variety of reasons, the fact remains that emergence of gaps in the escalation ladder, which increasing doubts over the credibility of US conferred military advantage to the Soviet Union extended deterrence instantaneously translate by virtue of its geography, paved the way for the into renewed debate about the need for nuclear granular nuclear architecture of the peak of the weapons within different European countries. Cold War, in which different types of shared systems all played their part. Critics frequently but erroneously remark that the tactical nuclear weapons delivered by dual THE CURRENT RELEVANCE OF NUCLEAR- capable aircraft have no military utility anymore. SHARING While the political cohesion logic may well have Much of the logic of nuclear-sharing remains been the overriding preoccupation in keeping relevant today. Nuclear-sharing constitutes the nuclear-sharing in place during the period in foundational core of alliance cohesion in the which Russia was seen to be a partner rather than nuclear domain: it ties different allies together in as a competitor, it is equally true that such way that is altogether unique. Different allies nuclear-sharing continued to have a latent subscribe to facing the responsibilities, risks and function of military flexibility, namely that of burdens that relate to nuclear deterrence keeping a minimal level of nuclear capability and together. The NATO Nuclear Planning Group – expertise alive in different allies, pending further from which France continues to abstain – has steps