Introduction

Brexit was an exceptional development in British politics. Withdrawal from the EU was in the area of economics and politics rather than in security and defence. However, the extent to which the UK would be able to continue to cooperate with its European allies militarily became an important aspect of the UK’s role adaptation after Brexit. Military cooperation between the UK and its European allies, in fact, ties in with questions pertaining to what kind of power the UK is and what kind of power it wants to be. For more than 60 years, the UK had relied on a close partnership with the USA alongside active engagement in Europe. Both pillars were questioned following the 2016 Brexit referendum, putting the UK in the position of ‘awkward inbetweener’ (James Strong cited in Bevington and Wright 2018).

Nevertheless, the UK remains a heavyweight in European security from a military point of view, having ‘full spectrum’ power projection capabilities (HM Government 2021a, 22, 60). On the final day of the NATO summit in Madrid in June 2022, incumbent Prime Minister Boris Johnson (quoted in Cameron-Chileshe 2022) pledged to increase UK military spending to 2.5 per cent of gross domestic product. Johnson’s successor as Prime Minister, Liz Truss, suggested in a speech to United Nations general Assembly in September 20,022, that the figure would increase to 3 per cent by 2030 (Truss 2022). Traditionally, the UK has a strategic culture that tolerates military intervention and the use of kinetic power (International Institute for Strategic Studies 2019). The UK, therefore, remains a key actor in the military realm. With these premises, this article looks at how the UK has reoriented its role as a military power outside the EU. It argues that the UK can exercise military leadership unencumbered by the constraints of EU membership and that it has broadened the avenues of military cooperation with its European partners. Whilst such avenues predated Brexit, the UK seized upon the available opportunities to perform its role as a military and security actor after Brexit. Opportunity was accompanied by a sense of anxiety over a diminution of status, but the record suggests that the UK has successfully elevated its post-Brexit relationships with European allies.

This article proceeds as follows. The first section discusses how the UK faced a potential loss of influence after Brexit. It then considers the opportunities which have presented themselves so allowing it to adapt its role as a military power outside of the EU. Here, the article considers the UK’s role in NATO, its leadership of the Joint Expeditionary Force (JEF) and the development of bilateral security relationships with individual European countries. It concludes by drawing out some of the implications of the UK’s continuing position as a leading European military power.

The UK’s role as a military power and the Brexit-induced loss of influence

Before Brexit, debates about the UK’s role as a military power revolved around the UK playing an important role in NATO, the UK being a preferred partner of the US and a key ally for Washington in the EU. This categorization is broadly in line with much of the literature on British foreign policy strategy, taking Winston Churchill’s influential view of the three interconnected circles of influence as its starting point (Gaskarth 2013; Niblett 2015; Oliver and Williams 2016; Whitman 2016). Whilst there was contestation over which of the three circles the UK should prioritise, when to do so, and why, there was a broad understanding that the UK ‘belonged’ in every circle no matter what. Besides, the UK had the opportunity to take part in discussions and decision-making within individual circles. This could open up space, for instance, for the UK to propose its own approach. Back in 2010, the First Secretary of State William Hague, for instance, argued that the UK should seek to work with many of the smaller states of the EU in new and more flexible ways (Hague 2010).

As a top-notch military power, the UK could, it seemed, take its elevated diplomatic position for granted. But as Brexit unfolded, questions were asked of the UK’s international standing (Dunn and Webber 2016). Debate focussed on which circle of foreign policy to prioritise (should the UK seek closer attachment to EU? Or should it continue to prioritise the special relationship with the US?) But this belied a deeper uncertainty about where the UK belonged and, related, about the UK’s great power credentials. This was not a matter of leaving the EU; it was also about the UK renegotiating and rebranding its role in the international system. After all, Brexit could change both the UK as a country as well as its standing in the world (Oliver and Williams 2016). Prime Minister Theresa May articulated this position succinctly in January 2017: ‘[…] to leave the European Union […] means more than negotiating our relationship with the EU. It means taking the opportunity of this great moment of national change to step back and ask ourselves what kind of country we want to be’ (HM Government 2017).

As the UK sought to chart its course outside the EU, there was uncertainty and anxiety about the ways in which it might continue to cooperate militarily with its European partners (Black et al. 2017). As noted in Webber’s introductory article, the supporters of Brexit did not see leaving the EU in negative terms. It was, rather, an opportunity for the UK to aspire to a better status. Still, Brexit brought about a loss of influence. At the end of the Brexit transition period in December 2020, the UK formally withdrew from EU’s Common Foreign and Security Policy (CFSP) and its offshoot, the Common Security and Defence Policy (CSDP). In anticipation, of this watershed, in July 2018 command of EU NAVFOR—Operation Atalanta—was moved from Northwood just outside of London to Rota in Spain (Council of the EU 2018). In December 2020, the UK ended its 16-year period of service in EUFOR, the EU deployment in Bosnia-Herzegovina (European External Action Service 2021; European Parliament 2021). Placed outside of relevant EU institutions (the Foreign Affairs Council and the Political and Security Committee), the UK lost its voice over what missions the EU might decide to launch and over the priorities and duration of existing EU deployments. This was a not insignificant disadvantage. While the UK had never been a major contributor to such missions, its involvement in EU bodies still gave it a formal say over their initiation and operational scope. As of 2020, the EU had, under CSDP, mounted a total of 34 military and civilian operations in 21 separate countries (Fiott 2020, 7). The UK also ceased participation in European satellite navigation programmes—Galileo and the European Geostationary Navigation Overlay Service (EGNOS) (HM Government 2021a; b, c). This represented a significant loss. However, the UK launched its own satellite navigation system in June 2022 (Titcomb 2022). Moreover, with Brexit, the UK lost its voice in discussions on EU sanctions (Mills and Smith 2021) and defence-related budgetary allocations (the European Peace Facility and the European Defence Fund).

The actual relationship between the EU and the UK on matters of security and defence remains a work in progress: it was not mentioned in the EU-UK trade and cooperation agreement (TCA) of 24 December 2020 (HM Government 2020). The UK has ultimately opted for a ‘muddling through’ approach, avoiding an overarching framework for EU-UK foreign, security and defence policy cooperation, in line with the UK seeking ad hoc arrangements for cooperation when and where it deems these to be necessary (Whitman 2020, 227).

To what extent should this lack of forward-looking and institutionalised agreement on military cooperation between the EU and the UK constitute a worry for the UK? On the one hand, EU security and defence integration received a boost in response to Brexit (Jokela 2020). But as a ‘third country’, the UK is no longer represented in EU institutions and cannot participate in EU decision-making on external action, except where discussions are seen as directly relevant to the UK (Sweeney and Winn 2021). The UK, as noted, has no direct involvement in the CFSP and has no say over the trajectory of the EU as a security actor. If the EU’s pursuit of strategic autonomy was to lead to greater EU-NATO competition, the UK would no longer be in a position to negotiate and accommodate differences between the two.

On the other hand, this loss of influence can be tolerated as the UK does not regard the EU as a meaningful defence actor. European efforts to achieve strategic autonomy are still hampered by several constraints: profound capacity shortfalls that will be hard to close and even harder without the UK, divergences across all domains of national defence policies, otherwise called ‘strategic cacophony’ (Meijer and Brooks 2021, 10), varying threat perceptions and also differing views of China, something that has created notable rifts among EU Member States (Santander and Vlassis 2021). On top of that, the Ukraine war has strongly unified NATO, reprioritising its core task of collective defence (Bell 2022). In March 2022, the European Council approved the EU Strategic Compass (European External Action Service 2022) but made clear that a stronger and more capable EU in security and defence would develop complementary to NATO.

Remaining an influential NATO member state

A cornerstone of the UK’s influence is its position in NATO. This has remained highly significant since Brexit. London tends to use NATO as a supplement to bilateral defence and security partnerships with Washington and other European states (Sweeney and Winn 2021). London’s important position as a key ally cannot replace American dominance within NATO. The latter has manifested over time in terms of historical interest, institutional development, and policy initiatives (Webber 2009, 49–51). In Europe, however, the UK remains one of, if not, the most influential of NATO allies.

This standing was, of course, evident before Brexit. The UK was a major force in the establishment of NATO in 1949 and was a stalwart ally throughout the Cold War. The UK assigned its nuclear forces to the alliance and made a major contribution to conventional defence with the British Army on the Rhine. In the post-Cold War period, the UK has maintained this position of influence. Since the establishment of the post in 1951, the Deputy Supreme Allied Commander Europe (DSACEUR) has been occupied only by UK or German nationals. It has, since October 2004, been held continuously by a British army general. The UK has also hosted important NATO facilities. In 2010, the Allied Rapid Reaction Corps (ARRC) relocated from Germany to Gloucester under British command. Allied Maritime Command (MARCOM) has been based in Northwood since 2012. The NATO Intelligence Fusion Centre is situated at RAF Molesworth. These facilities are important but not exceptional. Facilities in Belgium, Germany, Italy, the Netherlands and Turkey, along with those in the UK, all sit under Allied Command Operations. Perhaps more noteworthy has been the UK’s material contributions to the alliance. It has been a significant player in all NATO’s major operational deployments since the 1990s—in Bosnia, Kosovo, Libya and Afghanistan. The Brexit watershed cannot alone explain the continuing high priority accorded to NATO. It is simply a continuation of a decades’ long position.

That said, NATO did offer a ready-made arena for the projection of British influence once the opportunities afforded by the EU had been closed off. What then are the patterns of that relationship? A first issue concerns capabilities. The UK is a militarily self-sufficient member of NATO. In response to the Russian invasion of Ukraine in February 2022, Germany announced a historic increase in its defence budget, whereby the Bundeswehr was set to receive €100bn lump sum investment from the 2022 budget (Neumann 2022). German defence spending could as a result overtake that of the UK. Even if this were to occur, the UK retains (alongside France) a historic standing as one of Europe’s principal military powers. Official NATO data show that in 2021, the UK sat second among NATO’s 30 allies, in absolute spending, after the USA. The UK’s attachment to defence spending has been constant since the 2014 Wales summit committed the NATO allies to spend at least two per cent of their GDP on the military by 2024. The UK is one of the few countries that has consistently met that target since 2014. Currently, the UK is among the nine countries, including the USA, that meets the target (NATO 2022a, b). Despite the fiscal demands of the COVID-19 pandemic, Prime Minister Boris Johnson made a pledge in November 2020 to increase defence spending by £24.1 billion over the next four years. Framed by the UK Spending Review that month, one estimate noted that real terms growth in the UK defence budget would up to 2024/25 be at a rate comparable to that of the five years to 2019/20. This did not, then, mark a significant increase in spending, but it did mean that the UK would remain ‘comfortably above NATO’s 2 percent target up to 2025 and beyond’ (Chalmers 2021: 2).

The UK has also retained its institutional influence. The UK continues to hold the position of NATO DSACEUR. This post reports directly to NATO Supreme Allied Commander Europe (SACEUR), head of Allied Command Operations (and dual-hatted as the head of American forces in Europe) and allows for influence-shaping in two ways. First, under the so-called Berlin plus agreement, the EU can use NATO assets for operations. This allows the DSACEUR to be the main point of contact and even operational commander of EU operations that draw on NATO assets. Second, the DSACEUR leads NATO force generation. In so doing, the DSACEUR liaises with NATO allies and encourages them to generate equipment for operational deployment. The DSACEUR operates as a NATO representative here, but it is not lost on his interlocutors that he (the post has always been male) brings with him a credibility derived from the UK’s military experience and reputation. This state of affairs did not change after Brexit. There was some initial political jockying and France lobbied to take the position on the basis that it should be held by country that was both a NATO and EU member. But this did not enjoy NATO consensus nor American support (a testimony itself to British standing in the alliance). Since the 2016 Brexit referendum, DSACEUR has seen two (British) turnovers—from General Sir Adrian Bradshaw to General Sir James Everard in March 2017, and from Everard to General Sir Tim Radford in April 2020.

The UK also obtained the position of Chair of the NATO Military Committee after Brexit. The holder is responsible for advising the North Atlantic Council (NAC) on military policy and strategy. The position is rotational and elected by NATO Chiefs of Defence. British Air Chief Marshal Stuart Peach assumed office in June 2018. The position is currently occupied by Admiral Rob Bauer from the Netherlands, who assumed office in June 2021. However, the fact Stuart Peach was elected represented a vote of confidence in the UK after Brexit. He became the first Briton to hold the position for twenty-five years. Under Peach’s guidance, the first NATO Military Strategy in over fifty years was adopted accompanied by a Concept for Deterrence and Defence of the Euro-Atlantic Area and a new Warfighting Capstone Concept. Peach was also instrumental in articulating and reiterating positions such as the need to avoid duplicating NATO and EU military structures, and keeping security and defence separate from Brexit negotiations (Davies 2017).

UK leadership in NATO has also been articulated at the highest levels of government. This has been most visibly achieved through the hosting of major summits. A mark of commitment and standing in the alliance, the UK is not alone in taking on this role. In the post-Cold War period, summits have been hosted by thirteen different allies. But the UK is generally regarded as a very competent host, and while summit agendas are primarily overseen by the Secretary General, the British government has exploited the advantages of proximity to push favoured issues (London helped engineer consensus on the 2014 Wales defence spending pledge, for instance). It is also clear that in offering to host the 2019 NATO Leaders’ meeting the UK was mindful of wanting to demonstrate its ongoing convening power while the Brexit process was in full swing. The decision to draft a new NATO Strategic Concept, meanwhile, was midwifed by Britain at that meeting (Niblett 2021).

In terms of its practical contribution to NATO, the UK has scaled up its commitment to NATO’s mission in Iraq. It has also deployed 800 troops as the framework nation of the enhanced Forward Presence (eFP) in Estonia. In response to Russia’s mobilisation against Ukraine, the number of NATO troops stationed in Estonia under British command rose to 2,000 as of March 2022 (NATO 2022a, b). This is an important signal. British forces also deployed to Finland to take part in exercise Arrow in April 2022 and committed 1000 troops to the US-led exercises Defender and Defender Europe (Ministry of Defence 2022).

Further, the UK emerged in 2022 as the leading European provider of military assistance to Ukraine in its defence against Russia (Kampfner 2022). It was the first European country to provide Ukraine with ‘lethal’ weaponry and was, alongside the USA, instrumental in setting up the International Donor Coordination Centre in Germany to better organise military supplies. Building on the £350 million of military aid and around £400 million of economic and humanitarian support that the UK had already furnished, Prime Minister Boris Johnson announced in April 2022 that the UK would provide a further £100 million package worth of military aid to Ukraine. This included more than 800 anti-tank missiles, Javelin anti-tank missiles, loitering munitions, Starstreak air defence systems, and non-lethal aid including ballistic helmets, body armour and night vision goggles (HM Government 2022). In June, Secretary of Defence Ben Wallace announced further measures including the supply of three M-270 multiple-launch rocket systems. That same month at NATO’s Madrid summit, Boris Johnson announced a £1 billion package of UK assistance. As of mid-July 2022, the UK had committed £2.3 billion in military supplies to Ukraine (Mills and Curtis 2022). In parallel, the UK launched Operation Interflex with the aim of training up to 10,000 Ukrainian military personnel every 120 days. Several NATO allies and partners (Canada, Denmark, Finland, Lithuania, New Zealand, the Netherlands, Norway and Sweden) announced they would take part in this effort (Mills 2022: 9).

These initiatives paralleled US policy, but did not always, involve the Americans directly. The UK demonstrated a certain strategic discretion, but an independent role for the UK (or, indeed, for any other European power) to fill in for the US in NATO is hard to imagine. The UK, both over Ukraine and on other matters, has continued its historic role in the alliance of complementing American leadership. Following President Biden’s decision to withdraw troops from Afghanistan, London convened emergency talks at the G7 to rally support from other capitals with a view to working out a common approach to the crisis (Parker and Williams 2021). Whilst the initiative failed, it still showed the UK’s willingness to lead an important initiative diplomatically.

Exercising intra-alliance leadership: the promise of the Joint Expeditionary Force

Up to Russia’s annexation of Crimea in 2014, European defence capabilities had atrophied despite the best efforts of NATO and the EU at stopping the rot. The 2014 Wales defence spending pledge occurred at a moment when European states finally took it upon themselves to reverse decline. In parallel, the development of flexible, multinational military forces capable of mounting rapid operations came increasingly to the fore (Reeve 2019). The UK was a key mover in this regard. By making its defence policy more international by design—including the development of combined military formations such as the Joint Expeditionary Force (JEF), Britain, the government contended, would ‘improve the combat power and wider influence’ which it could bring to bear on prospective crises (HM Government 2015a).

The new form of cooperation entailed the formation of multinational forces under the leadership of a framework nation. NATO officially adopted the framework nation concept at the Wales summit in September 2014. This approach involved a major power providing the military backbone for a group of smaller participating countries with the intention of strengthening regional ties and improving inter-operability (Hagström and Sjökvist 2019). There are two key European defence collaborations that involve the pooling of military capabilities in this way: one is the Framework Nations Concept (FNC) led by Germany and the other is the JEF led by the UK. The JEF and the FNC were the result of economic pressure and the need to exercise intra-alliance leadership (Saxi 2017). Therefore, the JEF is a notable example of UK military dynamism. It shows how the UK has taken the initiative in creating what one senior Royal Navy officer (cited in Monaghan 2022) has described as a ‘force of friends, filling a hole in the security architecture of northern Europe between a national force and a NATO force’. Benefits of this type of collaboration include the promotion of quicker decision-making whilst contributing to fairer burden-sharing within NATO. Moreover, flexible coalitions with a framework nation can strengthen regional security ties and improve interoperability (Hagström and Sjökvist 2019).

The JEF is a high readiness, multi-domain military force that draws resources from ten countries: the UK as its framework nation plus Denmark, Estonia, Finland, Latvia, Lithuania, the Netherlands, Norway, Sweden and Iceland, which was the last to join in April 2021. The JEF’s main geographical area of operations is the High North, the North Atlantic and the Baltic Sea region. Of the participating states, Dutch forces are the most capable and integrated with those of the British (Reeve 2019). The UK has opted for a select group of countries with whom it shares a common outlook and existing military ties. In that respect, the JEF is different from the German-led FNC, which gathers a broader and, in some cases, less capable group of countries in Northern and Central Europe.

The JEF reached full operational capability in July 2018 with the signing of the comprehensive memorandum of understanding by the defence ministers of all nine partner nations plus the UK. The JEF is not a NATO structure, but it has a NATO connection. It uses NATO standards and military doctrine as its baseline and it can be used to support UN, NATO or other multinational or coalition operations. The group of countries that conduct operations do not need consensus to act. A formation under its aegis could, therefore, respond quickly to a crisis. The UK may conduct a JEF activity with the involvement of one or more participants; there is no obligation of the remaining number to contribute forces. Committing forces to a JEF mission remains a sovereign national decision for participating nations, in line with their respective legal frameworks (HM Government 2021b).

The JEF exceeds the ambition of the UK-French Combined Joint Task Force (CJTF), unveiled in 2010 as the UK and France signed treaties at Lancaster House on defence and security. Whereas the CJTF has a combined command structure, the JEF partners operate under British command. The JEF clearly serves the purpose of keeping the UK connected to its European partners (Zandee 2017). The JEF is intended to be a flexible, UK-led force of up to 10,000 personnel available for overseas deployment, including combat, peacekeeping and humanitarian operations (Reeve 2019). It is committed to a balanced range of capabilities within the maritime, land, air, space and cyber domains (HM Government 2021b). For the UK, the security policy of the JEF is about positioning the UK as an important European defence partner post-Brexit whilst demonstrating British leadership in a NATO context. The JEF seems to fit the following criteria in terms of establishing whether multinational collaborations can work. First, multinational military formations are more likely to be successful if participating countries trust one another. Second, they should be geographically proximate. Third, they should share historical ties and fourthly, participation should be extended to a manageable number of countries (Zandee et al. 2016; Saxi 2017).

The JEF is not about the UK becoming dependent on other allies but about enabling trusted partners to opt into British-led operations: allies’ capabilities that the UK lacked, such as the Dutch military’s Patriot ground-based air defence missiles, would be desirable rather than indispensable (Saxi 2017). Whilst the JEF is a promising avenue for the UK to exercise leadership in European security, Jakobsen et al. (2018, 257) caution that ‘states become coalition contributors for multiple reasons’ and those reasons can ‘oscillate over time’. In September 2021, MoD Permanent Secretary David Williams met with the nine counterparts from the JEF and discussed the achievements of JEF to date (HM Government 2021c). This included a Royal Navy presence in the Baltic Sea with the frigates HMS Lancaster and Westminster, and the tanker RFA Tiderace operating alongside vessels from the three Baltic states (Royal Navy 2021). In September 2021, JEF headquarters were relocated to Sweden to take part in exercise Joint Protector with the aim of enhancing multilateral operational command post-cooperation between JEF countries (Finnish Defence Forces 2021).

Russia’s invasion of Ukraine has made the UK’s commitment to re-establishing its long-standing role as a military power on NATO’s northern flank more important and the JEF is an important component of this. The leaders of the JEF’s participating states, for instance, agreed they would coordinate funding and the supply of military equipment to Ukraine and that they would carry out joint exercises to deter further Russian aggression (The Economist 2022).

Deepening bilateral relations with individual European countries

Agreements on the terms of UK withdrawal from the EU did not come up with any structured mechanism to associate the UK with CSDP civilian and military missions. UK demands for some form of special tailored ‘third party’ arrangement came to nothing. British involvement would, therefore, have to occur on a case-by-case basis. But there was not, in any case, any presumption that the UK held a desire to engage in such operations. The only exception to this state of affairs would be missions arranged multilaterally between the EU and NATO where the UK could participate under the ‘Berlin plus’ mechanism. But here too the possibilities seemed limited. Since Berlin plus was formalised in 2003, only one mission—EUFOR in Bosnia—had been run under its auspices (Mills and Smith 2021, 4–5).

Given these limitations, the UK has prioritised bilateral defence collaboration with individual EU Member States. This has developed considerably since Brexit. Upgrading bilateral relations has been an important component of the ‘Global Britain’ agenda (Von Ondarza and Mintel 2022). Accordingly, the UK has concluded several bilateral security agreements with EU countries. This includes Finland and Sweden, both of which signed up to security declarations (albeit not formal treaties) with the UK in May 2022. At that point, the two Nordic countries had just submitted formal requests to join NATO. The arrangements with the UK thus offered some reassurance against possible Russian destabilisation while their applications were being considered by the NATO allies. For the UK, the two declarations signalled a continuing commitment to protect NATO’s eastern (and northern) flanks—a priority for the region following Russia’s invasion of Ukraine in February 2022.

In addition, the UK had concluded bilateral security agreements with Estonia in March 2021, followed by joint declarations and partnership agreements with Germany, Latvia, Denmark, Belgium and Greece. The UK’s commitment to strengthening defence relations with the Netherlands should also be noted. (Von Ondarza and Mintel 2022). Whilst the above bilateral agreements are all important signs of the UK’s willingness to maintain close ties with members of the EU, the strengthening of the UK’s ties with France and Germany deserves further consideration in the light of the importance of the Franco-German tandem at the centre of the EU (Krotz and Schild 2018).

Anglo-French defence cooperation remains the most important security relationship that the UK has in Europe. The relationship builds on a track record of cooperation which pre-dated Brexit. Back in 2010, British Prime Minister David Cameron and French President Nicholas Sarkozy announced a new programme of defence cooperation and also promised to deliver a subordinate treaty relating to a joint nuclear facility (HM Government 2010). Under the terms of that treaty, the UK and France would build two joint nuclear research facilities, one in Valduc, France and the other in Aldermaston. As Lord Ricketts (2020) reminds us ‘by 2018, the UK and France were using the same vast radiographic machines for their national experiments’. The UK has also supported the French-led European intervention initiative (EII). At the Franco-British summit in Sandhurst in January 2018, President Macron and Prime Minister May (quoted in Mauro 2018) affirmed their desire to ‘create within a group of European states the conditions for future commitments in various scenarios of military intervention’. President Macron launched a new initiative called ‘European Political Community’ in May 2022. The UK supported the new initiative through its participation in the initial meeting of 44 countries in October 2022 (Fella 2022). Furthermore, showing its continuous willingness to maintain a link with Europe in the realm of defence capabilities, the UK delivered full validation of the combined joint expeditionary force (CJEF) in 2016 following the bilateral Exercise Griffin Strike in the UK, involving over 5000 UK and French military personnel (Ministry of Defence, n.d.). CJEF then reached full operational capacity in November 2020 as it could rapidly deploy over 10,000 personnel in response to a wide range of tasks including high intensity operations, peacekeeping, disaster relief and humanitarian assistance (Brader 2021). In parallel, the UK and France cooperate in various regions such as Mali (Operation Barkhane), the Middle East (as part of the wider global coalition against Daesh) and Estonia (under NATO’s enhanced forward presence) (Monaghan 2021).

The UK has also sought to deepen its defence and security relationship with Germany. The UK Government announced in 2010 that British forces would be withdrawn from the country by 2020 (HM Government 2010). 20,000 army personnel left by the deadline, leaving behind only 185 British army personnel and 60 Ministry of Defence civilians. The UK did, however, retain training sites for the British army, and UK and German continued to collaborate on a combined driver crossing capability. As van Rij and Wilkinson (2021, 8) have noted ‘[t]he M3 river crossing capacity led to the integration of joint unit British and German units for a capability in short supply in NATO’. In October 2018, British Defence Minister Gavin Williamson and his German counterpart Ursula von der Leyen signed a joint vision statement which signalled the renewed commitment of the UK to European security. This built upon two prior occurrences: in 2015, via its Strategic Defence and Security Review, the UK promised to deepen its defence relationship with Germany as well as the USA and France (HM Government 2015b). Germany followed suit as the 2016 German defence white paper emphasised its ‘security partnership with the United Kingdom, which has a long tradition and which we aim to further expand in all areas of common interest’ (Federal Government 2016). Secretary of State Dominic Raab and his German counterpart followed up by signing a joint declaration of intent in June 2021. Some commentators (for example, Urbanovská et al. 2022) still assess the bilateral relationship between the UK and Germany as underdeveloped in areas such as defence and industrial cooperation. Nevertheless, there is track record of work in place that suggests a mutual desire to develop ties post-Brexit (Wintour 2021).

Conclusion

Following the 2016 Brexit referendum, the UK reaffirmed its role as a military power in European. The UK seized upon available and unfolding opportunities to perform this role. The UK has remained a very influential member of NATO, exercised intra-alliance leadership via initiatives such as JEF and deepened bilateral cooperation with several European allies. This suggests that the UK has successfully managed to elevate its relationship with European allies outside the EU. There are implications here for the UK’s position and European security more broadly. First, the strategic autonomy of the EU is downplayed. Whilst the UK cannot try to limit the further development of the EU as a security actor, it can make use of its position in NATO to make sure duplication does not take place. Secondly, a strengthening of clusters in European security could take place. By leading initiatives such as the JEF, for instance, the UK has come to promote a more flexible approach to European security cooperation. This comes with some advantages: it can promote fairer burden-sharing and strengthen regional security cooperation. Thirdly, as a military power outside the EU but which has sought to deepen bilateral relationships with individual European countries, the UK can count on being trusted by states who need defending (Lucas 2022). In this connection, the Ukraine war has revealed the importance of the UK as a military power. Russia’s invasion of Ukraine has served as a stark reminder that NATO continues to hold the position of Europe’s most meaningful security institution, somewhat side-lining the concept of ‘European strategic autonomy.’

To conclude, the UK is likely to remain a ‘go to’ ally on military matters. Its role adaptation following Brexit has shown the potential to further amplify the UK’s position as a security provider for Europe through NATO. The UK can continue to lead initiatives of its own—the JEF and bilateral agreements being examples of a coherent UK approach to defence multilateralism in Europe that is parallel much more with NATO than it is with the EU.