Brexit’s implications for EU-NATO cooperation: Transatlantic bridge no more?

Abstract

Since its accession to the European Union, the United Kingdom has played an important role in the design and development of the European Union’s foreign, security and defence policy. While it is among the founding members of North Atlantic Treaty Organization, it is also one of the main contributors to European security and played an active part in developing the relationship between both organisations. With the United Kingdom’s decision to leave the European Union, questions concerning the implications of Brexit on European Union–North Atlantic Treaty Organization cooperation arise. As the transatlantic bridge between the two organisations, Britain also faces an uncertain position within the European security architecture. It therefore needs to redefine its relations with the European Union and its own position among other member states. Taking into account the development of national security interests and recent political events, this article develops three possible scenarios that may occur for the European Union–North Atlantic Treaty Organization relationship depending on the outcome of the Brexit negotiations.

Introduction

British policymakers and strategies have long mentioned North Atlantic Treaty Organization (NATO) as the cornerstone and prime guarantee for the United Kingdom’s security and defence, and the European Union as the most important organisation for economic and trade issues. During the Cold War, there was a clear division of labour between the two organisations, whereby NATO was responsible for collective defence and the European Union (EU) was tasked to enhance regional integration. The end of the Cold War triggered a rethinking of European security and brought about an identity crisis within the Atlantic Alliance, while the EU sought to distinguish itself as a security and defence actor through developing the Common Foreign and Security Policy (CFSP) and the Common Security and Defence Policy (CSDP). In the course of these organisational developments, member states found themselves in a situation where they felt the necessity to choose between either of these two organisations or to support a new form of cooperation in international security.

With its decision of 23 June 2016 to leave the EU, the United Kingdom will not face this question anymore. However, uncertainty about its future relationship with the Union, not only in regard to trade and economics but also in the field of foreign, security and defence affairs, prevails with the ongoing negotiations on the future relationship between the EU and the United Kingdom. The Brexit referendum made sway for new initiatives for defence cooperation within CSDP such as Permanent Structured Cooperation (PESCO) and the European Defence Fund (EDF), which were otherwise blocked by the United Kingdom. At the same time, the country leaves a gap in the EU’s military capabilities and external relations because of its specific resources and expansive network of diplomatic relations. Concurrently, the EU and NATO have come closer and enhanced their relationship in which Britain has traditionally played a key role whereby it can be labelled as the transatlantic bridge between Europe and North America and between the two organisations. It is thus vital to examine the impact of the Brexit decision and the future EU-UK security and defence relationship on the interorganisational relationship between the EU and NATO.

Recent analyses have focused on the future relations between Britain and the EU with a particular emphasis on the outlooks for a future partnership in foreign, security and defence affairs. These primarily circulate around different options for their relationship and what position the United Kingdom might take, the implications for the future EU-UK and UK-US relationships, and different scenarios on post-Brexit security cooperation (Baciu and Doyle, 2019; Bond, 2016; Duke, 2018; Hadfield, 2018; Martill and Sus, 2018; Oliver and Williams, 2016; Whitman, 2016). What has been less explored in previous studies is the impact of Brexit on the EU-NATO relationship. While arguments exist for Brexit being an enabling factor for closer cooperation and a potential trigger for European strategic autonomy (Round et al., 2018; Von Voss and Schütz, 2018), this article investigates the United Kingdom’s role in the interorganisational relationship between the EU and NATO in security and defence up to the 2016 EU referendum, and how this role might change in the course of the country’s departure from the Union.

In this context, it is assumed that the United Kingdom can be labelled as an advocate of interorganisational interaction and as the bridge between the EU and NATO due to its long-standing contributions to the institutionalisation of their cooperation and its ‘“networked” foreign policy’ (Whitman, 2016: 44). With regard to Brexit, it has the potential to have a knock-on effect on the revamped EU-NATO relationship, and the United Kingdom might also have the potential to become a future blocker and spoiler of this special interorganisational relationship, which will depend on the outcome of the Brexit negotiations and Britain’s future security and defence agreement with the EU as a non-EU NATO member state. The main question addressed here is what implications Brexit could have on EU-NATO cooperation. While analysing Britain’s position therein, this article proposes three scenarios on the impact of Brexit on this special relationship.

Conceptualising the United Kingdom as the ‘transatlantic bridge’

Over the course of time, the United Kingdom has filled different positions within both the EU and NATO. It belongs to the group of original or old member states (Magliveras, 2011), and it is also among the big and more powerful states. Yet, it is more difficult to classify the country per se into a specific group or category of member states in terms of the interorganisational relationship between the EU and Atlantic Alliance. Conceptualising the role of the United Kingdom as a bridge draws on the literature of international regime complexity and network analysis and has also roots in Waltz’ neorealist work on the levels of analysis (Alter and Meunier, 2009; Drezner, 2009; Gehring and Faude, 2014; Jönsson, 1986; Waltz, 1959). Deriving from these approaches, the re-emerging research programme of interorganisational relations offers helpful findings for the study of member states in the relationship between international organisations and provides insights into their strategic choices to shape their behaviour in interorganisational interaction (Biermann and Koops, 2017; Hofmann, 2009, 2019; Koops, 2012). Gehring and Oberthür (2009) acknowledge that member states play vital roles in shaping the institutional design and interactions between organisations. Yet, the literature on the role of member states in interorganisational interaction is sparse and the analysis of the impact of the withdrawal of a key member state is still underexplored in these debates. The conceptualisation of United Kingdom as a particular member state therefore contributes to the study of member states’ roles in interorganisational relations.

Drawing on the literature of interorganisational relations, regime complexity and network analysis, interactions between international organisations occurs ‘if one institution (the source institution) affects the development or performance of another institution (the target institution)’ (Gehring and Oberthür, 2009: 127), and the phenomenon can be further defined as the interactions, links and relations between at least two international organisations in the same policy field. Among the pre-conditions for interorganisational interaction to take place is the overlap of interests, norms and functions including policies, areas of operation and responsibilities, which can be caused intentionally or unintendedly. These overlaps can then trigger either cooperation or competition and rivalry among international organisations (Gehring and Faude, 2014). Further key aspects of interorganisational interaction are states’ membership and specifically membership overlap since states are the foundation of international organisations. In addition to functional and geographical overlap, membership overlap counts as a decisive factor for interorganisational cooperation since states play the profound role and driving forces in foreign, security and defence affairs. Moreover, it can be distinguished between different types of membership (Magliveras, 2011). Whereas original or old member states are the initiators and creators of international organisation, which gives them the privilege to determine the design, purpose and functioning of the organisation at their discretion, subsequent or new member states need to apply to access the already established organisation, which gives them less power to influence the organisational evolution.

States can furthermore be classified as either single or multiple members. Single members are those states which are only member of one of the organisations involved in interorganisational interaction. This allows them to shape the actions, policies and interactions of one organisation but limits their ability to exert any influence on the partner organisations. Yet, single members can make use of strategies such as advocacy, obstruction and hostage-taking. The latter is a strategy in which ‘states that are members of just one institution can use their membership to obstruct the relationship between both institutions, holding them hostage in pursuit of narrow interests’ (Hofmann, 2009: 46). However, multiple members have membership of both organisations of the concerned interorganisational relationship. With the help of multiple memberships, these states have an even greater pool of strategic options, labelled as ‘cross-institutional political strategies’ (Alter and Meunier, 2009: 16). These strategies include forum-shopping, that is the ability to select a preferred organisation for the course of action and the realisation of interests which can lead to clearly defined division of labour between overlapping organisations, and regime-shifting, which enables states to also select the preferred organisation with the aim to change the structures of rules, as well as turf battles, that is expanding one organisation’s area of responsibility and action, and muddling through, which illustrates informal ways of cooperation due to certain constraints. Multiple members can additionally act as brokers in which they facilitate coordination and push for a division of labour between overlapping organisations while also balancing divergences among other member states (Alter and Meunier, 2009; Gehring and Faude, 2014; Hofmann, 2009, 2019; Koops, 2012). Although all states can pursue these strategic choices, ‘only the great powers will possess the capabilities necessary to enforce, implement or resolve [interorganisational] disputes’ (Drezner, 2009: 67). In its position as transatlantic bridge, the United Kingdom has made use of forum-shopping since it favours NATO for defence and deterrence while it prefers the EU for diplomacy and foreign affairs, and consequently, it promotes a clearly defined division of labour.

Furthermore, the United Kingdom’s position within the EU-NATO interorganisational relationship can be defined as an old, big and multiple member state. Furthermore, it has been labelled in numerous ways which all lead to conceptualising the United Kingdom as an advocate of interorganisational interaction and especially as a bridge between the EU and NATO. For example, Oliver and Williams (2016: 547) call the United Kingdom the ‘transatlantic bridge’ and Bailes (1995) characterises the philosophy of Britain’s defence policy as ‘active, global, multinational and intergovernmental’, and well-resourced and well-staffed which overall concedes it to become involved in numerous international organisations at the same time. Hofmann (2019) refers to the United Kingdom as a broker in terms of executing the EU and NATO’s mandates as it has made use of informal channels and bilateral partnerships to advance the interorganisational relationship. Whitman (2016: 44) consequently calls the United Kingdom ‘a “networked” foreign policy actor’ because of its high degree of bilateral and minilateral agreements and cooperative links to other strategic actors and states. These include its membership in key international organisations besides the EU and NATO such as its permanent seat in the United Nations Security Council and memberships in the Council of Europe, International Monetary Fund, Organisation for Security and Cooperation in Europe, and World Bank. Within both the EU and NATO, Britain has taken particular positions. As an original member state of NATO, the United Kingdom has been an active contributor to the Alliance’s operations and institutional developments. Within the EU, Britain has often presented itself as the ‘awkward partner’ in terms of developing CFSP and CSDP, and only agreed to institutionalising and developing the EU’s security and defence policies once NATO’s continuous dominance in European security and defence affairs was ensured (Howorth, 2000).

Its special relationship with the United States has been helpful to maintain the transatlantic link and has been reflected in the United Kingdom’s Atlanticist approach to defence (Cornish, 2013). This special relationship has allowed the United States to keep a foot in Europe, which has become increasingly relevant in the course of the United States pivot towards Asia-Pacifica and also enabled the United Kingdom to play a more profound role within the Atlantic Alliance. In addition, its defence and security cooperation with France through the 1998 Saint-Malo Declaration and the 2010 Lancaster House Treaties, as well as its membership in informal coalition groups including the so-called ‘Friends of Europe’ ¹ , the ‘Quint’ ² and the Big Three with France and Germany are of great importance for the United Kingdom to promote its ideas, interests and policy preferences concerning the EU-NATO relationship (Ewers-Peters, 2017, Interview with Official at the British Delegation to NATO, 20 July, Brussels).

As a ‘globally significant player’, Britain has the ability to contribute actively to enhancing interorganisational cooperation (Whitman and Tonra, 2017). In addition to its widely spun diplomatic service and its military budget amounting to 2.2% of GDP (SIPRI, 2017), it is among the top five military powers in the world. Even beyond the military sphere, the United Kingdom is ranked among the top five countries with the highest GDP in 2016 (World Bank, 2018). In interorganisational and network analysis parlance, its key strategic position as well as its preference for functioning and proactive cooperation between the EU and NATO, Britain acts as a ‘linking-pin’ actor. This position is attached to an actor who serves as a linkage between one organisation and other actors, including states and organisations in the same policy environment, and therefore, it can function as key ‘communication channel’ and coordination hub (Jönsson, 1986: 42). This is usually taken by, what Koops (2017: 201) labels, an ‘interorganisational hegemon’, that is, a state that possesses the willingness and the required resources to influence the relationships between two or more international organisations as well as the ability to shape policies, preferences and interests of international organisations. Yet, despite its active involvement and taking the lead in advocating for enhanced cooperation between the EU and NATO, some member states have doubted the United Kingdom’s willingness to specifically develop and contribute to the EU’s CSDP. This has triggered Rodt (2017) to classify the country as ‘lead state’ as well as a ‘swing state’, but as the following analysis will show, the United Kingdom has primarily served a broker and therefore as a bridge between the EU and NATO.

With the United Kingdom’s withdrawal, the EU will lose a key player in its security and defence structures and one of the most militarily capable member states. While this is not the first time that a member state decides to leave an international security organisation – other examples include Morocco’s withdrawal from the African Union and France’s disintegration from NATO’s integrated military command structures in 1966 which it re-joined in 2009 – it is a decisive moment for interorganisational cooperation. Brexit will trigger the departure of the ‘interorganisational hegemon’ (Koops, 2017: 201) in the EU-NATO relationship which is expected to impact the effectiveness and viability to implement the proposals to enhance practical cooperation between the two organisations. Moreover, chances are that the United Kingdom itself will lose its key position as a transatlantic bridge since it will no longer have a seat on the EU’s decision-making table, and thus, it will not be able to advocate for United States and NATO security and defence interests anymore, once it fully departs the Union.

Acting as the bridge between the EU and NATO

As a long-standing member of NATO and the EU, Britain has been considerably active in shaping each organisation in their capabilities and strength as defence and security actors. While, according to its national security and defence strategies, NATO has traditionally been named as the country’s ‘cornerstone’ and most important channel for security and defence, the EU is identified as the United Kingdom’s preferred forum for international trade, diplomatic relations and foreign policy (Ewers-Peters, 2017, Interview with Two Officials at the British Permanent Representation to the EU, 24 October, Brussels). Despite its initial reluctance to build up an autonomous European security and defence capability and policy in the 1990s, it nevertheless played a vital part in advancing CFSP and CSDP through its institutional commitments and military capabilities. Moreover, it has been supportive of enhancing cooperation between the EU and NATO. As an advocate of interorganisational relations between the EU, the United States and NATO (Oliver and Williams, 2016: 547), the United Kingdom has served as this ‘transatlantic bridge’ on two levels: (1) institutional level and (2) operational level. This section explores its involvement and contributions to EU-NATO cooperation in more depth by examining the United Kingdom’s bridging role on these two levels.

Institutional level

This sub-section examines the extent to which the United Kingdom has contributed to the development of the legal framework and the institutionalisation of the EU-NATO relationship. Britain’s role is primarily highlighted by its active participation and engagement. The formalisation of interorganisational relations is seen as relevant for setting the framework as well as for defining the boundaries and opportunities for areas of cooperation.

In the discussions among states and policymakers on developing European military capacities and a European security and defence policy (ESDP), it has often been stressed that the United Kingdom came across as the reluctant and obstructing actor. This position resulted from the negotiations surrounding the Treaty of Maastricht in which United Kingdom’s opposition to the creation of new institutional security and defence structures in Europe due to the existing ones in NATO became evident (Howorth, 2000; Miskimmon, 2004). Yet, throughout the 1990s and early 2000s, the United Kingdom played a fundamental role in contributing to developing the structures of the ESDP and in shaping the institutional design of the EU-NATO relationship as it advocated for formal contacts between the EU and the Atlantic Alliance. It acted as a watchdog to ensure the avoidance of any duplication and competition on the one hand and to guarantee complementarity with NATO’s command and institutional structures on the other hand (Howorth, 2000; Rees, 1996). This illustrates the British belief in pragmatism concerning security and defence organisations in Europe with special regard to pragmatic solutions to economic constraints and restraints in numbers of personnel (Cornish, 2013; Ostermann, 2015).

Moreover, the Franco-British Summit in Saint-Malo in December 1998 marks a significant milestone for the EU-NATO relationship, which was initiated by then Prime Minister Tony Blair under whose government a shift towards European integration in security and defence was recorded. The two countries discussed the idea to create a European capability for autonomous action in order to improve Europe’s readiness for responding to international crises and to strengthen the transatlantic link. Both countries, however, had different objectives because ‘whereas Britain saw capability development as a means to strengthen the transatlantic relationship; France perceived it as a means to strengthen the EU as a foreign and security policy actor’ (Simón, 2017). Blair further emphasised that the EU would take on the role of security actor, but the defence dimension would remain solely with NATO (Biscop, 1999; Dryburgh, 2010; Dyson, 2011; Miskimmon, 2004). To find an agreement, the United Kingdom set the condition that the EU would be able to acquire autonomous military capabilities and develop a security and defence policy, albeit limited to crisis management and the Petersberg Tasks, and only in close cooperation and consultation with NATO. The United Kingdom sought to trigger reforms and increase the military capabilities among member states to support both NATO as well as the EU (O’Donnell, 2011). As a consequence of the Saint-Malo agreement, EU member states furthered the development of the ESDP, and both the EU High Representative and the NATO Secretary General began to meet informally.

Britain eventually accepted the institutional development and the inclusion of a defence dimension within CSDP, which highlighted the change in the United Kingdom’s domestic policy and how it has ‘swung back and forth between more or less pro-EU positions’ (Rodt, 2017: 139). In addition, it was active in defining the European Security and Defence Identity (ESDI) within the Atlantic Alliance. It originally perceived the ESDI as an opportunity to strengthen the military capabilities among other European member states, and due to its long-lasting special relationship with the United States, it acted as ‘interlocutor’ between Europe and North America (Rees, 1996: 232). In this context, supporting both the ESDI in NATO and the development of ESDP allowed Britain to bridge the interests of its European partners and the United States as well as of NATO and the EU at the same time. Britain provoked an important step towards the establishment of formal relations between the EU and NATO. It played a significant part particularly in the early beginnings in enabling the institutionalisation and formalisation of the EU-NATO relationship while more actively promoting the necessity for cooperation among member states in both arenas.

British officials under the Blair government were heavily involved in the procedures that resulted in the Berlin Plus arrangements between the Union and the Alliance. They vocalised both concerns and opportunities for cooperation on military capabilities. Eventually, they were able to convince the Turkish officials to agree, who were initially opposing such arrangements on sharing NATO’s military assets and capabilities. British officials held bilateral negotiations with Turkey as well as with both organisations in order to overcome any oppositions and disagreements, which allowed the signing of the agreement of the Berlin Plus arrangements (Missiroli, 2002). In the same year, the United Kingdom brokered a compromise between NATO and the EU, more specifically with those states that participated in the so-called Chocolate Summit in Tervuren, that is, Belgium, France, Germany and Luxembourg, which later led to the establishment of permanent liaison cells at NATO’s SHAPE and in the EU Military Staff (Duke, 2008).

Finally, as the analysis by Koops (2012) demonstrates, staffing of key positions has become an important factor for member states to pursue their interests concerning interorganisational cooperation. Former Prime Minister Tony Blair was not the only British official who has actively advocated for closer EU-NATO cooperation, but also other representatives and officials have filled key positions to bridge the two organisations. For example, the British diplomat Lord George Robertson served as NATO Secretary General – while Javier Solana presented the EU as its High Representative for CFSP – and had previously been appointed as Defence Secretary. According to one NATO Official, the proactive drive for enhanced cooperation was most fruitful during the Robertson-Solana era because of their shared vision of European security as well as their friendly personal ties. He even went further to label this era as the ‘best period of cooperation’ (Ewers-Peters, 2017, Interview with NATO Official at NATO HQ, 29 March, Brussels). In this context, it needs to be noted that during the 1990s, the amicable UK–US relationship under Tony Blair and Bill Clinton alongside the UK’ EU-friendly orientation has further helped Britain to bridge the two sides of the Atlantic. Another key position filled by a British representative is the operations commander for EUNAVFOR Atalanta. This was particularly useful because the United Kingdom provided the operational headquarters for both the EU-led Operation Atalanta and the NATO-led Operation Ocean Shield in the Gulf of Aden (Gebhard and Smith, 2015), which will be further elaborated in the following sub-section.

While the United Kingdom played an active part in formalising EU-NATO cooperation in the early beginnings, the era of the 2010s mostly saw years of silence between the two organisations. In the lead-up to the 2016 Joint Declaration, Britain was also pre-occupied with the preparations for the EU referendum. Nevertheless, according to British Officials, the United Kingdom sought to foster its position within the Euro-Atlantic sphere by ensuring the role of single member states. During the negotiations of the 2016 Joint Declaration, it thus tried to play an active part to secure its own status especially in regard to the future security relationship with the EU (Ewers-Peters, 2017, Interview with Two Officials at the British Permanent Representation to the EU, 24 October, Brussels). Stronger EU-NATO cooperation has become more important with the outcome of the EU referendum, and henceforth, Britain is seeking to ensure smooth channels of communication and interaction in order to stay in the information loop.

Drawing on its wide network of bilateral relationships and its embeddedness in multilateral security cooperation frameworks inside NATO and the EU as well as outside these two organisations, the United Kingdom plays an important role in advocating their approaches to security and defence as well as their cooperation efforts in the area of crisis management. Thus, Britain acts as a ‘linchpin’ actor (Jönsson, 1986) that connects states and international actors alike. Over the course of time, it has effectively contributed to the formalisation process of the EU-NATO interorganisational relationship through its widely spun networks and linkages as well as by filling key positions with officials who saw the benefits of enhanced cooperation.

Operational level

Multilateral military crisis management operations rely on the contributions by their member states. The density of international organisations, especially in Europe, has the potential to trigger competition among those organisations that seek to be in charge of initiating and deploying troops. Member states therefore choose carefully and with specific rationales and interests which organisations they prefer for the launch of civilian and military operations. In some instances, more than one organisation receives the mandate and resources, including troops and military capabilities, in the same theatre, which can trigger interorganisational cooperation or competition. Key aspects to induce interorganisational cooperation in the same crisis situation include member states’ contributions to these operations as well as their effort to increase interoperability. Although the United Kingdom has often been accused of its lack of commitment to and inconsistent support for European security and defence (Biscop, 2012), it has advocated closer cooperation with a specific division of labour. This sub-section thus illustrates the United Kingdom’s contributions on the operational level.

The United Kingdom as one of the most prominent advocates also provides among the highest contributions to EU-led and NATO-led military operations. Its armed forces are of high quality despite the severe cuts and austerity measures over the years, and with its possession of nuclear deterrent, the country enjoys a special status in both organisations (Hill, 2018). Since the end of the Cold War, Britain has participated in every single NATO-led operation, including those in Bosnia and Herzegovina (Operation Joint Endeavour and IFOR/SFOR), Kosovo (KFOR), FYRo Macedonia (Operations Essential Harvest, Amber Fox, Allied Harmony), Afghanistan (ISAF, Resolute Support), Libya (Operation Unified Protector) as well as the naval operations in the Mediterranean Sea (Operations Active Endeavour, Sea Guardian) and in the Gulf of Aden/Horn of Africa (Operations Enduring Freedom, Ocean Shield). Concerning EU-led operations, Britain contributed to all of the recorded operations so far, which include operations in the Western Balkans (Concordia in FYRo Macedonia, Operation Althea in Bosnia Herzegovina) as well as numerous operations in the Sahel and Africa including in the Democratic Republic of Congo (Operation Artemis, Operation DR Congo), in Chad and the Central African Republic (EUFOR Chad/CAR), in Mali (EUTM Mali), the naval operation in the Mediterranean Sea (Operation Med Sophia), and deployments to Somalia and the Gulf of Aden (EUNAVFOR Operation Atalanta, EUTM Somalia; Eilstrup-Sangiovanni, 2014; EU, 2016; Grevi et al., 2009; NATO, 2016).

By participating in EU and NATO operations, the United Kingdom has proven to be essential for the cooperation between the EU and NATO. For example, during the negotiations and conduct of NATO’s operations and the EU’s Operation Concordia in FYRo Macedonia, it ‘played a crucial bridging role between Europe and the United States in the Berlin Plus negotiations’ (Rodt, 2017: 132). It was during this crisis that the final provisions were agreed for the Berlin Plus arrangements based on the lacking military capabilities on the EU side. Furthermore, in Operation Althea, British Major General Leakey filled the position as the first Operation Commander and thereby made a major contribution to the EU’s takeover from NATO’s SFOR operation. Throughout his term, Leakey was in frequent exchange with the main chief-of-command, which was still located within NATO (Grevi et al., 2009; Rodt, 2017). In terms of the 2011 Operation Unified Protector in Libya, the United Kingdom alongside France was the initiator of the military intervention despite its initial reluctance to engage. Consequently, the country emerged as part of the leadership group of European security and defence. After the deployment of an EU-led operation in Libya failed, the Franco-British joint intervention was conducted under the NATO framework. This did not only boost their defence cooperation but the intervention as a whole also demonstrated Europe’s willingness for military operations while pleasing the United States’ demand for more European responsibility and perceived leadership. Britain thereby contributed to higher degrees of collaboration and interoperability between European and US forces and between EU and NATO forces (Howorth, 2013; Johnson and Mueen, 2012).

In the case of the naval operations in the Gulf of Aden and Horn of Africa, the United Kingdom has played a key part by providing the operational headquarters in Northwood for both naval operations – EUNAVFOR Operation Atalanta (since 2008) and NATO Operation Ocean Shield (2009–2016). A shared operational headquarters allow for a smoother communication and exchange of information between the two organisations as well as the efficient use of member states’ capabilities. Providing the operational headquarters enabled the United Kingdom to play a contributing act towards EU-NATO cooperation as it consented to the launch of EUNAVFOR Operation Atalanta albeit its initial reservations (Gebhard and Smith, 2015). It specifically argued that a new operation would not be needed because NATO and the United States were already operative in the area (Nováky, 2015). Britain finally agreed to launch an EU-led naval operation as favoured by its defence ally France, while it also continued to support the NATO-led operation which included the involvement of its special partner the United States. By means of providing the operational headquarters and agreeing to the deployments, the United Kingdom created a coherent link between the EU and NATO and their member states.

According to its 2010 and 2015 national security and defence strategies, the United Kingdom aims to improve interoperability of its armed forces and weaponry with other EU and NATO members, and especially with the United States. The United Kingdom stresses the importance of interoperability especially in terms of information sharing and logistics with its key allies, the United States, France and Germany (United Kingdom (UK), 2010a, 2015). Through its bilateral cooperation with France based on the 2010 Lancaster House Treaties, it ensures further interoperability, for instance, through the development of a Combined Joint Expeditionary Force and the joint usage of its aircraft carrier in addition to cooperation on satellite communications, cyber security, unmanned air systems and research and technology (UK, 2010b). Similarly, the United Kingdom has been cooperating with the United States on information and intelligence sharing beyond the NATO framework, which further enhances interoperability due to increased shared awareness. The continuation as well as the added value for interoperability between the EU and NATO has thus been frequently emphasised (UK, 2015).

Moreover, the aspect of division of labour has received increased attention with an emerging closer cooperation between the EU and NATO. While their responsibilities and tasks were clearly defined during the Cold War – NATO as the defence alliance in charge of collective defence and territorial security and the EU as a political project responsible for economic and political integration – this changed with the new security environment in the 1990s. The United Kingdom believes that a division of labour between the two organisations leads to more consultations and the reduction of the capability and interoperability gaps, because with a clear mandate and a well-defined set of tasks and responsibilities each organisation can develop the required capabilities. According to one EU official (Ewers-Peters, 2017, Interview with EU Official at EEAS, 3 April, Brussels), it was admitted that there will always be overlaps and duplications to a certain extent, but additional duplication can be avoided through a defined and negotiated division of tasks.

Advocative states like the United Kingdom maintain a long record of participation and contributions to multilateral military crisis management efforts under the EU and NATO frameworks. Britain acknowledges the challenges with interoperability of armed force and seeks to overcome them by facilitating better communication and exchanges within their armed forces. By collaborating with states outside these frameworks, the United Kingdom created a wide network of linkages that are beneficial for EU-NATO cooperation. Through its contributions it has not only supported the development of the EU’s security and defence policy and capabilities, but also added essential elements to its interoperability with the Alliance. Nevertheless, because there is no clearly defined division of labour or geographical scope, the United Kingdom makes use of its armed forces and contributes to both EU and NATO military crisis management operations on case-by-case decisions to support each organisation’s advantages and strengths. This has added to their interorganisational cooperation and capability to act.

Brexit and its future implications for the EU-NATO relationship

With the decision to leave the EU in June 2016 and the approval of the Withdrawal Agreement by the European and British Parliaments in January 2020, the United Kingdom’s international role will ultimately change. Britain as well as both organisations will need to adapt to the new circumstances. Some would argue that a hard Brexit, that is, the complete withdrawal from the EU’s Single Market and Customs Union and the discontinuation of EU law for the United Kingdom, would strengthen NATO since the internal functioning of the Alliance will carry on as usual and thereby weaken the EU’s foreign, security and defence policy (Ewers-Peters, 2017, Interview with EU Official at EEAS, 3 April, Brussels). Yet, Brexit would also have implications for Britain’s position in the European security architecture which would have a potential knock-on effect on the revamped EU-NATO relationship. With the Withdrawal Agreement between the EU and the United Kingdom (2019), the two have entered a transition period in which EU law still applies but disallows the United Kingdom to participate in decision-making including in foreign, security and defence affairs. The extent of these implications and consequences, however, will depend on their future security and defence agreement with Britain as a non-EU NATO member state.

A European Union without the United Kingdom will affect European security and stability as a whole because it would lose one of its most powerful member states and direct access to its capabilities and resources, including intelligence, manpower, military assets, diplomatic services and nuclear deterrent. With ongoing negotiations on the future EU-UK relationship, several options for their future security relations and the United Kingdom’s commitment towards European security and defence policies have been formulated by Martill and Sus (2018) as well as the United Kingdom (2018) Government itself. First, the United Kingdom will remain committed to European security and defence and Brexit will not have a great impact. Britain will become a third country, which is common practice, and will be able to contribute to CSDP missions and operations on the basis of a Framework Participation Agreement. Second, the United Kingdom will focus on its participation and commitments in NATO. It is likely that future security relations will be carried out through the EU-NATO relationship. Finally, is it assumed that the United Kingdom will expand its already wide network of bilateral and minilateral security relations which will also include EU member states. The existing Franco-British security and defence cooperation has been effective and since the Brexit referendum in 2016, Britain has already started to sign similar, though less deep and formalised, agreements with Poland and Germany. Based on these three options, it is likely that future security cooperation will primarily take place through EU-NATO cooperation and bilateral relationships (Von Voss and Schütz, 2018), which creates incentives for Britain to pursue an agreement on security and defence cooperation with the EU while also strengthening NATO. The relations with the United States will also become even more significant to secure Britain’s standing in international politics and to ensure the realisation of their common interests. For the purpose of this article, the future EU-UK security arrangement and the implications of Brexit can also affect the EU-NATO relationship in different ways that lead to the development of three possible scenarios in the following, that could occur depending on the outcome of the Brexit negotiations and the future arrangements between the EU and the United Kingdom.

In the first scenario, the United Kingdom leaves the EU with a negotiated deal that includes arrangements on close cooperation in security and defence affairs, provisions for the exchange of information and intelligence as well as a bespoke Framework Participation Agreement to allow Britain’s smooth participation in EU-led crisis management operations and Battlegroups. This scenario roots in their shared security threats, current tensions in the transatlantic relationship, and the acknowledgement that security and defence in Europe require coordination and cooperation with European partners. Such a close EU-UK security and defence relationship facilitates the United Kingdom to retain its position as the bridge between the Union and NATO and to further advocate actively for enhanced cooperation. As a soon-to-be single member state, close interaction and cooperation between the EU and NATO allows Britain to be part of exchanges and consultations and to exert some influence on their agenda. Seeing that the United Kingdom has always been ‘half in, half out’ (Hill, 2018: 157) of European foreign and security policy, it is expected that this will not change and that both sides desire close collaboration in line with previous cooperation during the United Kingdom’s EU membership. Britain would also contribute to CSDP operations in the future in terms of providing personnel and financial resources. The United Kingdom would also receive a special third-country status within the EU’s foreign, security and defence policy, which would allow the continuation of its role as the transatlantic bridge between the EU and NATO and between Europe and the United States. As the best-case scenario, this would ultimately – ceteris paribus – lead to the implementation of the proposals set out in the EU-NATO Joint Declarations, such as coordinated and parallel military exercises, enhancing military mobility, and information exchanges. Considering that much of the positive attitudes and goodwill between the EU and the United Kingdom have passed during the negotiations, for this scenario to occur, both sides need to regain trust and see the benefits of a functioning cooperation in foreign and security affairs, which require to be formalised in the future partnership agreement. This scenario also requires Britain’s future embeddedness in the Single Market and Customs Union so that Brexit’s fiscal impact on the United Kingdom’s economy will be limited and thus its capacity to provide for security and defence in Europe will be ensured (The UK in a Changing Europe, 2020). This would benefit the EU and NATO since Britain would be able to maintain its current level of military expenditure of 2.2% of its GDP. While it is unlikely that EU member states will give Brexit-Britain any decision-making power on security and defence affairs, close coordination and consultations on new initiatives would be expected since cooperation also takes place in minilateral forums. Subsequently, this enables Britain to transfer security preferences and interests.

Alternatively, in the second scenario, the United Kingdom leaves the EU with a negotiated deal but one that minimises the importance of collaboration on foreign, security and defence affairs. Britain will be treated like any other third party and both parties agree on a Framework Participation Agreement that is similar to those of other non-EU NATO member states (Tardy, 2014). According to this scenario, cooperation between the EU and the United Kingdom would occur on an ad hoc basis and focus on the commitment of the United Kingdom’s networks and diplomatic relations as well as its resources and capabilities including intelligence, combat aircrafts, specialised expeditionary forces and, above all, its nuclear deterrence. This scenario predicts that the United Kingdom will maintain ties to the EU’s economic zone, though weak ones and in the form of piecemeal agreements. This would also affect the defence industry and consequently, Brexit’s fiscal and economic impact will affect the United Kingdom’s defence spending and limit its own capacity to contribute to security and defence either in NATO or with its European partners. Both the EU and United Kingdom continuously state that they seek a close post-Brexit security relationship. Under this scenario, cooperation on specific issues such as intelligence sharing, terrorism and sanctions will continue with individual EU member states. Britain will seek to collaborate through bilateral and minilateral security agreements, such as those already in place with France, Germany and Poland. While this arrangement facilitates the United Kingdom’s participation in crisis management operations, it would not allow to shape any policies or agendas and thus, the United States – and NATO – will lose the ability to exert indirect influence. In this weakened position, the United Kingdom would seek to strengthen its transatlantic relations with the United States to enhance its own standing in NATO and globally to remain a significant international player. For the future of the EU-NATO relationship, this means that the United Kingdom will not be able to serve as the bridge anymore and the country is rather likely to emphasise its commitments to NATO. This suggests that Britain would strive for enhanced bilateral security and defence cooperation particularly with France and the United States as well as other key partners as already outlined in its 2018 Assessment of the Security Partnership (UK, 2018; also see UK, 2015). Bypassing the EU-NATO framework would subsequently lead to greater imbalance between the two organisations which results in more difficulties to implement the proposals and would overall decelerate EU-NATO cooperation.

From a more pessimist view, in the third scenario the United Kingdom crashes out of the EU without a negotiated deal and the process of making arrangements for a future EU-UK security relationship will take time, which are likely to be based on piecemeal deals and clusters of bilateral arrangements with the United Kingdom’s closest partners. Concurrently, Britain will focus on strengthening its own position within NATO and in the world whereby it will pursue the strategy of Global Britain (see Hill, 2018). The lack of an agreement and the United Kingdom’s exit from the Single Market and Customs Union will trigger economic consequences since EU member states make up the main trading partners, which will also affect Britain’s acquisition of defence capabilities and access to joint capability development projects of its EU partners (Heisbourg, 2018). On the EU’s side, Brexit and the lack of a future security and defence agreement means that other EU member states will need to compensate and thus acquire more capabilities and assets despite their austerity-driven defence budgets. The newly introduced initiatives by the EU, particularly PESCO and EDF, highlight the window of opportunity created by Brexit and already hint at deeper integration and the strengthening of defence capabilities by EU member states. It is assumed that Brexit has in fact triggered not only greater solidarity among the EU27 but also greater interest in strengthened security and defence policies and capabilities within the EU (Cini and Verdun, 2018; Martill and Sus, 2018). The United Kingdom will no longer be able to represent the Atlanticist, and thus the American, interests in the EU decision-making and policy-shaping in security and defence, which would catapult the United Kingdom as a new outsider in European security and defence affairs. Nevertheless, this is likely to lead to closer United Kingdom–United States ties in both economic and security terms, which might lead to a stalemate and might even trigger a new split between the EU and NATO because of an emerging disconnect. While the EU will pursue the further development of its own defence structures, and potentially move closer to European strategic autonomy, this will raise new concerns within the Atlantic Alliance and thus hamper the enhancement of EU-NATO cooperation (Round et al., 2018). For the United Kingdom, this means that it will not be able to serve as ‘linchpin actor’ (Jönsson, 1986) anymore and eventually lose its role as the transatlantic bridge between the EU and NATO. Even more, it might lose its overall international status due to the loss of financial resources to provide for security and defence as well as the loss of crucial cooperative relationships with its key partners in Europe. Moreover, the United Kingdom might spoil future initiatives for closer EU-NATO relations, such as the effective cooperation on defence industry and intelligence sharing as it will rather seek to cooperate bilaterally or only within the NATO structures. For the future EU-NATO relationship, this means that other member states might seek to take over this role – Poland and Estonia are likely candidates – and that cooperation and coordination will primarily take place between their international secretariats, i.e. the European Commission with the European External Action Service and NATO’s International Staff.

As these three scenarios show, the United Kingdom’s withdrawal from the EU and its foreign, security and defence policies will nevertheless trigger consequences on the relationship between the EU and NATO, most specifically on their interoperability, formalisation of cooperation and member states’ contributions to military operations. Since it has made major contributions to the interoperability between the two organisations on the operational level, such as in the case of their involvement in the Gulf of Aden and Horn of Africa, the United Kingdom after Brexit will find it difficult to serve as a bridge between the armed forces once Brexit is fully completed (Bond, 2016). It could still take over bridging functions under a Brexit with a strong EU-UK security and defence cooperation agreement, though it would be absent from decision-makings which would be vital in the promotion of their cooperation as well as lose its right to veto initiatives that might lead to duplication and decoupling. In this context, a caveat needs to be mentioned. It is rather unlikely that, as in the case of the first scenario, any British Prime Minister would agree to commit armed forces to EU military operations under CSDP without having a say in command decisions. Therefore, cooperation on an ad hoc and minilateral bases within European non-EU security and defence frameworks, such as the European Intervention Initiative (Ei2) proposed by French President Emanuel Macron, would be more likely (Heisbourg, 2018). Furthermore, Brexit will also have implications on the formalisation process and the institutional arrangements between the EU and NATO. Since the end of the Cold War, the two organisations made significant progress in developing these institutional arrangements for cooperation and has managed to deal with several veto players, especially single member states such as Cyprus, Turkey and the United States (Duke, 2008). The United Kingdom could become an additional spoiler and blocker, whereby its ability to mediate between the US-dominated NATO and the French-driven EU would be heavily constrained, if not even nullified (Hastings Dunne and Webber, 2016; Oliver and Williams, 2016).

The actual consequences of Brexit for the EU-NATO relations remain to be seen. While the extent of these implications is not yet clear, it is evident that there will be intended as well as unintended, underlying implications for the interorganisational relationship between the two organisations. Aside from Brexit, the implementation of actions to strengthen EU-NATO cooperation is still in progress since the signing of the 2016 and 2018 Joint Declarations and has seen successful actions in the areas of maritime security, hybrid warfare and political dialogue. Several other factors, however, affect their relationship such as the changes in the security environment, overlapping threat perceptions, capability developments and the future directions of both NATO and the EU in security and defence affairs. Due to its embeddedness, linkages and military capabilities, the United Kingdom will nevertheless continue to play an important part for European peace, security and stability and it will be in the interests of all actors concerned to keep Britain inside this framework.

Conclusion

The aim of this article was twofold. First, it sought to explore Britain’s role in the relationship between the European Union and NATO. The United Kingdom is conceptualised as the bridge between both sides of the Atlantic, and especially between the two organisations on the institutional and operational levels. Since the end of the Second World War, NATO has been its cornerstone for security and defence, but it has nevertheless played an essential part in the development of the EU’s structures and capabilities. From the early beginnings of EU-NATO interorganisational interaction, the United Kingdom has been heavily involved in the institutionalisation process. With the help of its embeddedness in both organisations and its special relationships with other states and actors, especially with both France and the United States, it was able to contribute to strengthening EU-NATO cooperation. On the operational level, Britain has participated in all EU and NATO operations and provided the operational headquarters for their deployments in the Gulf of Aden, which allowed the country to create a link between the two organisations. Overall, the United Kingdom has so far illustrated well the extent to which it can serve as the bridge between the EU and NATO.

Examining the potential implications of the United Kingdom’s withdrawal for the EU-NATO relationship was the second aim of this article. While it is widely acknowledged that Brexit will effectively have an impact on European security and defence, the extent is not yet observable. It is evident, however, that the United Kingdom will no longer be able to play the bridge between the Union and the Atlantic Alliance the way it did before and that it is very unlikely to be the first point of contact for other member states in terms of this interorganisational relationship. This article presented three possible scenarios for Brexit on the EU-NATO relationship – one in which the United Kingdom will continue to play an important part in enhancing their cooperation, one in which the United Kingdom will become just another non-EU NATO member state and the relationship will slow down, and one in which Brexit will trigger an imbalance and thus a stalemate in EU-NATO cooperation. The future of this special interorganisational relationship will depend on the future EU-UK relationship and how the EU and NATO will deal with the new circumstances of having another potential obstacle among their member states.