STUDY Matthias Dembinski u a nd Hans-Joachim Spanger June 2025 D NA ie T u O n’s gewisse Z U u n k ce u r n t f a t in de F r u N tu A r T e O

Imprint Published by Friedrich-Ebert-Stiftung e.V. Godesberger Allee 149 53175 Bonn Germany info@fes.de Issuing Department International Cooperation Division| Department for Global and European Policy Responsibility for content: Peer Teschendorf| European Foreign and Security Policy peer.teschendorf@fes.de Translation Meredith Dale Design/Layout pertext| corporate publishing www.pertext.de Cover picture picture alliance/ NurPhoto| Artur Widak The views expressed in this publication are not necessarily those of the Friedrich-Ebert-Stiftung(FES). Commercial use of media published by the FES is not permitted without the written consent of the FES. Publications by the FES may not be used for electioneering purposes. June 2025 © Friedrich-Ebert-Stiftung e.V. Further publications of the Friedrich-Ebert-Stiftung can be found here: ↗ www.fes.de/publikationen

Matthias Dembinski, Hans-Joachim Spanger June 2025 NATO’s Uncertain Future

Content Foreword .........................................................  3 Introduction ......................................................  4 1 Threat perceptions and risks ......................................  6 Russia: The central threat .........................................  6 China: A rival but not(yet) a threat .................................  8 The southern dimension: Ongoing security risks .....................  10 Hybrid threats: War in the twilight zone...........................  11 2 How to tackle the threats? .......................................  13 Defence spending: How much is enough?..........................  13 Conventional defence: capability gaps and dual risks .................  16 Nuclear deterrence reloaded ......................................  16 3 Ukraine’s place in the European security architecture .................  18 4 Dealing with Trump: Transatlantic hopes and European visions........  20 5 The future of NATO: Three development paths ......................  23 References ......................................................  26 Overview to the study series ........................................  27

Foreword Exactly four years ago, the Friedrich-Ebert-Stiftung published its first study on NATO. Its opening sentence read: “The future of NATO is once more under discussion.” By that time, Russia’s annexation of Crimea in 2014 had al ready prompted a recollection of the importance of al­ liance defence, and the Afghanistan mission had raised fundamental questions about military interventions. The Alliance had set itself the goal of developing a new strategic concept to respond to the changed situation and new challenges. In preparation, our initial study aimed to understand how key members envision NATO’s future, what they consider to be NATO’s primary tasks and in which areas they think the Alliance should act. The publication, which appeared in June 2021, was an accurate reflection of the state of the discussion and stimulated debate on the role of NATO. In February 2022, NATO’s future seemed to be decided for the time being. With Russia’s war against Ukraine and the end of the remaining security order in Europe, NATO returned to its traditional role as the main guarantor of security in Europe for decades to come. Other fields of activity and problems that had been the subject of intense debate in recent decades receded once again into the background. However, the challenges posed by the first war of aggression in Europe since 1945 exposed weaknesses and dependencies within the Al­ liance, reigniting the debate about burden-sharing and the role of the European states within the Alliance. With US President Donald Trump’s second term in office, the question of NATO’s future has nevertheless returned with new urgency and a significantly different portent. While the main point of contention in 2021 was still the appro priate response to external challenges, questions about NATO’s internal constitution are now at the forefront. Although the issue of burden-sharing within the Alliance has been central for decades, the question of the role of the United States has not. This study aims to capture the current debate on significant security challenges and the future of NATO in key member states and among some non-members. The war in Ukraine has once again made it clear that threats are assessed and prioritised differently within the Alliance and that these assessments are linked to different expectations of NATO. With this study, the Friedrich-Ebert-Stiftung aims to clarify the discourse dynamics in various countries and security policy contexts. Therefore, the study includes countries on the eastern and southern flanks, as well as Central European countries. It is also important, however, not only to portray the debates of the large member states, but also to make visible the views of smaller and more recent members. For a consensus-based organisation like NATO, understanding the views of all its members is of fundamental importance for developing joint plans. This is particularly true if the Alliance has to manage without the central integrating effect of a benevolent hegemon. This summary is based on the expertise of the many experts who prepared the country analyses. We would like to thank each of them for their contributions. The transformation into a whole greater than the sum of its parts is primarily due to the intensive support of Hans-Joachim Spanger and Matthias Dembinski from the Peace Research Institute Frankfurt(PRIF), who also provided the synthesis of all the studies in this text. We would like to express our sincere thanks for the good and productive cooperation on this publication. Our hope is that it will stimulate the debate on the future of NATO. Peer Teschendorf Berlin, June 2025 Foreword 3

Introduction Prior to the Russian invasion of Ukraine in 2022, NATO was contemplating its purpose. Three options were on the table: → A return to collective defence in Europe; → Geographical enlargement, with closer cooperation with the East Asian democracies, an enhanced role in counter-terrorism, and crisis management in the southern neighbourhood; → Functional expansion, taking on additional responsibilities such as energy security and hybrid threats, and/or emerging challenges like climate protection or the role of women in peace and security. In the 2021 version of this study, we designated these var iants“NATO classic plus”,“NATO with a global outlook” and“NATO Generation Z”(Dembinski and Fehl 2021). While the scenarios remain valid, Russia’s invasion of Ukraine in February 2022 has put collective defence firm ly back on the table. Faced with Russian aggression in their immediate neighbourhood, NATO’s European members regard the organisation as absolutely vital for their security. This has been NATO’s greatest challenge in the past fifty years – and the organisation has delivered. The Alliance met Russia’s aggression with renewed cohesion and determination. The accession of Finland and Sweden has significantly strengthened its geostrategic position in Europe’s critical northeastern region. It has significantly expanded its defensive capabilities with NATO’s New Force Model and the regional defence plans, deployment of additional US forces, and collective moves towards meeting the 2 per cent target for defence spending, con firmed in 2014. On top of all that came the unprecedent ed support for Ukraine’s defence against the Russian invasion. However, the war and the elevated threat scenar­ ios have also exposed grave deficiencies: empty depots, munitions shortages, outdated equipment, lacking personnel. In short, the legacy of the post–Cold War Peace Dividend. Essentially all member countries share the new sense of determination. There are, however, differences – as laid out already in the 2021 study – associated with their size, geo graphical location, history and political culture. Turkey is a prime example. The country treats NATO principal­ly as a kind of insurance. Turkey would prefer the Alliance not to interfere in its autonomous and increasingly as­sertive foreign policy – but it should offer protection in the event of blowback from foreign adventures. In order to cover the range of differences, we selected a sample of eleven of the thirty-two member countries: the United States as the leading power; France, Germany, the Netherlands and the United Kingdom as middle powers in NATO’s centre; Poland and Lithuania representing NATO’s eastern flank, Italy and Turkey for the southern flank, and the two new Nordic members Finland and Sweden. To complete the picture, we also included the Ukrainian, ­Russian and Chinese debates on NATO. The exhilaration of 2022 was not to last. Deep and poten tially existential crisis followed in autumn 2024. After the external threat from Russia had welded the Alliance together, Donald Trump’s re-election as US president blew it apart again. Trump and his acolytes see NATO primarily as a burden and the European members(and Canada) as freeloaders. It is currently unclear whether the Alliance retains any relevance in light of Trump’s very narrow definition of national interests. Even worse, Trump’s initiatives – imposing tariffs on friend and foe alike, aggressively claiming territory from NATO member Denmark and casually suggesting annexing Canada – harm the Alliance’s very core. The problem is that the United States is not just some peripheral member. It is the leading power. It sees itself – to quote former US Secretary of State Madelaine Albright – as“indispensable”. And the other members accept it as such, in view of its crucial – and for the time being irreplaceable – military capabilities and its material contributions. The United States still represents the classic case of hegemonic leadership: material, institutional and ideational. Donald Trump’s election forces NATO to reassess its role yet again. Externally challenged and internally weakened, it is uncertain if it has a future, and if it does, how it will look. The question of how it needs to change if it is to fulfil its mission and improve its chances of survival is both murky and hotly debated. Now, after the shock of 2022, the question is no longer whether collective defence is a relevant mission, but whether and how the mission can be realised collectively. 4 Friedrich-Ebert-Stiftung e.V.

The discussion revolves around three key questions: → Can the United States be kept on board? Will NATO remain a transatlantic alliance whose ability to act depends on US leadership? → Will the European partners accept the loss of hegemonic leadership? And will they attempt to substitute it through closer European coordination, up to and including effective integration of their national defence and armaments policies? → Or will NATO without the United States develop into an intergovernmental alliance of democratic states, overcoming impasses through flexible“coalitions of the willing”? In this situation, where NATO’s future is uncertain and open, it will be helpful to take a look at the political and expert discussions in the member countries in order to get a better idea of the potential shape and likelihood of alternative trajectories. Introduction 5

1 Threat perceptions and risks Russia: The central threat Russia represents the preeminent threat to the security of Europe(and potentially beyond Europe). This assessment is shared by the European members of NATO and Canada – and was by the United States until Donald Trump returned to office. This can be expected to prevail regardless of how the war in Ukraine ends. The causes of the threat, the Europeans believe, lie in a conflict encompassing security, values and international order. While that is the underlying consensus, differences are observed both within and between many of the member countries. This is already visible in the respective assessments of the level of tensions and the danger of war proliferating beyond Ukraine. Similar differences are found in views on the causes of the war , where we can identify two main camps. One sees Russian revisionism and imperialism as the reason for the Ukraine war. Russia, they believe, not only wants to restore the power and territory of the Soviet Union. It also wants to bend the European security order to its own preferences, which have nothing in common with the collectively agreed upon norms and institutions of the CSCE/OSCE. This camp believes that Moscow’s aggression will continue unabated after the war. But how a European order beyond military deterrence might actually look is entirely unclear and generally little discussed. An amicable settlement with Vladimir Putin’s Russia certainly appears inconceivable. Indeed, some proponents of this line believe it to be ruled out entirely by Russia’s Assessments of current tensions with Russia and future danger of war Germany United States Poland Finland Sweden Lithuania UK France Italy Netherlands Turkey Level of tensions high high high high high high high high high high medium Level of tensions/ Danger of war high medium low 6 Friedrich-Ebert-Stiftung e.V. Figure 1 Danger of war low low medium medium low medium low low low low low

imperialist legacy. Hence there is no place today for the kind of dual strategy of deterrence and détente that NATO pursued in the 1960s after the Harmel Report – and still less for concepts seeking cooperative security with Moscow. Proponents of this threat perception have been alarmed by Trump’s recent initiatives to end the war in Ukraine and lift Russia’s isolation. Peace at Ukraine’s expense, they say, would inevitably encourage Russian revisionism and imperialism. The danger of broader war in Europe is growing. The conclusion, for this camp, is that collective defence and the ability to defend against Russian kinetic warfare and major hybrid attacks must remain NATO’s core mission even after the end of fighting in Ukraine. And much work remains to be done if the deterrence is to be credible. Three principal causes are named: 1. The regime itself, the autocratic character of the Russian political system. 2. Russia’s historical legacy of expansionism and imperialism(independent of its current political system). 3. NATO, on account of the West’s denial of Russian (spheres of) interests. The idea that the West might be the cause of the war is virtually absent in Lithuania, Poland and Finland, but very prominent in Turkey. The Turkish government and aligned think tanks certainly regard Russia as a rival for influence in regions important to Turkey – Central Asia, the Caucasus, the Middle East and North Africa – but less as a direct threat to its own security. This lies behind Ankara’s multivectoral foreign policy. The second camp sees the West as primarily responsible for the war. This argument revolves around NATO’s(and the EU’s) successive expansion into the sphere of influence claimed by Russia after the end of the Soviet Union – conceding that it is in the nature of major powers(which must include Russia since Putin’s restoration) to claim such a sphere. From this perspective, challenging the sphere of influence was bound to create conflict. Moreover, the West’s proclaimed values of democracy, rule of law, sovereign equality and rules-based international order have been used to justify hegemonic ambitions and unwarranted ­interventions. As such they serve – in line with Moscow’s Expert discourses on the question: Cause of the Ukraine war of 2022 Figure 2 Country France United Kingdom Poland Finland Lithuania Sweden Netherlands Germany Italy USA Turkey Putins’ regime √ X √ X √ X √ X √ X √ X √ X √ X √ X √ X √ Russian imperialism √ √ X √ √ X √ √ √ √ NATO expansion √ √ √ √ √ √ √ X √ Dominant position √ Minority position Threat perceptions and risks 7

­interpretation – as a pretext for enforcing particular interests. This created a conflict dynamic that ultimately ran out of control. The prominent proponents of this line of argument include classical right-leaning geopolitical experts and left-leaning anti-imperialists, as well US neorealist circles around figures like John Mearsheimer. Their positions also find a hearing in Trump’s milieu. The Trump administration sees China as the greater threat – and in the long term the decisive one – while Russia is essentially a regional challenge affecting Europe. Trump’s“Make America Great Again” perspective rather foregrounds the missed opportunities with Russia. While this is primarily an economic question, the rivalry with China also makes it a strategic one(to the extent that such considerations play a role in the White House at all) in the sense of levering Moscow out of its alliance with Beijing. This position is not uncontested within Trump’s own party, and the Republican foreign policy hawks, who dominated the party’s security debate in the past, are working hard to be heard(as they did during Trump’s first term). This second evaluation is associated with various practical options. The need for military deterrence is generally acknowledged. But the need for negotiations is equally stressed – not only to end the war in Ukraine but also to find broader security arrangements, following the detente-­ era principle that Europe’s security“can be achieved only with Russia, not against it”. Ultimately this camp also includes proponents of the idea that NATO needs to stop or even reverse its expansion. China: A rival but not(yet) a threat Since the 2019 summit in London, NATO’s Secretaries-Gen eral have underlined the linkage of the European and East Asian theatres of conflict and the need for the Alliance to become more global. Outside of the United States, those calls have found a lukewarm reception among the member countries. However, the belief that China has become a“systemic rival” representing a challenge and increasingly also a threat is broadly shared – albeit with certain nuances. Expert discourses on the question: Deterrence or cooperative security? Figure 3 USA Italy Germany France United Kingdom Netherlands Sweden Finland Poland Lithuania Turkey Deterrence Majority opinion 8 Friedrich-Ebert-Stiftung e.V. Tendency  Cooperative security Minority opinion

The practical consequences remain modest, however. That also applies to the question of a stronger NATO engagement in East Asia as a quid pro quo for the US presence in Europe. Consultation and(security) coordination with the region’s democracies – Australia, New Zealand, Japan and South Korea(AP4) – is generally welcomed, but military contribu tions are ruled out. The latter would risk being dragged into unwanted conflicts, it is argued, and anyway Europe would have little to contribute in military terms. The parameters of the debate have shifted since Donald Trump’s re-election, and Washington’s confrontation with Beijing has stepped up several gears. This increases the risk of becoming embroiled in a situation where Europe is unable to exert any meaningful influence on Trump’s erratic unilateralism. And that puts a spotlight on the differ­ ences within NATO, with the United States(and Lithuania) representing the pole pressing for deterrence and de-coupling. Turkey is the opposite end of the spectrum, seeking to expand economic and political cooperation with China and even deepening institutional ties(such as Turkey applying for membership in SCO and BRICS). Most European NATO members find themselves somewhere in-between, continuing to pursue resilience and de-risking but finding themselves increasingly confronted with Washington’s demands for de-coupling. The picture is similar when it comes to the question of which organisation – NATO or the EU – is more suited to containing the identified risks and threats from China. There is no support for expanding NATO geographically; it remains tied to the territory defined in Article 6 of the NATO Treaty. But that does not exclude consultations, nor continuing cooperation with the AP4. However, mili tary deepening of these partnerships does not currently appear advisable: Trump’s erratic style greatly increases the danger of unpleasant surprises and reduces the attraction of offering European engagement in the Eastern Pacific in exchange for a continuing US presence in ­Europe. As far as the security implications of Chinese engagement in Europe are concerned, the EU remains by far the most appropriate instrument for coordinating action, both for Assessments of current tensions with China and future danger of war USA Litauen Polen Finnland Schweden Deutschland Frankreich UK Italien Niederlande Türkei None low Level of tensions medium Danger of war Figure 4 high Threat perceptions and risks 9

monitoring Chinese investments in critical infrastructure and in trade-related issues. For the moment there is consensus in the European part of NATO – including the US-­ leaning countries on the eastern flank – that a European East Asia strategy centred on economic and diplomatic means will be better placed to respond to the Chinese challenges – and that the EU is therefore the better platform. The southern dimension: Ongoing security risks Although member countries agree that collective defence is back at the top of the agenda, there are differences over how much energy and resources the Alliance should continue to devote to crisis management and the fight against terrorism. In other words, which other actors and developments – aside from Russia – threaten the security of NATO and its member countries, and to what extent. This applies both to traditional risks of terrorism, civil war and state failure, and to the novel threats associated with the growing Russian and Chinese presence in the southern neighbourhood. Here again our survey shows a clear north-south divide. While the members in northern Europe would not want to ignore the global risks, they are interested above all in a quid pro quo between the jointly acknowledged threat from the east and the interests of the NATO members on the southern periphery, who see explicit risks and threats in their own region. Turkey, however, is also pursuing genuine strategic interests of its own. However, crisis management is about more than allocating scarce resources. Most member countries have doubts whether NATO, as a consensus-based organisation, is the best framework for navigating the politically often fraught fight against terrorism. And after the humiliating failure of ISAF in Afghanistan and a whole string of other crisis management missions conducted by coalitions of Western states, there are fundamental question marks over the usefulness of such interventions. The fundamental question of the role NATO can and should play in this field reAttitudes to China; between deterrence and resilience, de-risking and de-coupling Germany United States Poland Finland Sweden Lithuania UK France Italy Netherlands Turkey Deterrence no yes no no no yes no no no no no 10 Friedrich-Ebert-Stiftung e.V. Resilience yes yes yes yes yes yes yes yes yes yes no Yes No De-risking yes yes yes yes yes yes yes yes yes yes no Figure 5 De-coupling no yes no no no yes no no no no no

turns here in heightened form. Four recommendations are under discussion. As a military organisation NATO possesses few comparative advantages in crisis management and interventions. Here the EU is better suited. → As a security actor NATO should play a stabilising diplomatic role, alongside support measures such as training missions and protecting humanitarian convoys. → NATO should remain involved in crisis management, but“coalitions of the willing” are operationally better suited. Crisis interventions should be delegated to such coalitions, with NATO assuming analysis and coordination functions and providing its infrastructure. → NATO should remain prepared for major crises in its southern neighbourhood with the potential to threaten European security and should retain its organisational capacity for crisis intervention. → The spectrum of opinions in our survey tends strongly towards the middle two options, which see NATO fulfilling above all a coordinating and supporting role. That also applies to experts in the southern member countries, who have doubts whether NATO as a military alliance can contribute meaningfully to political and societal stability in the southern neighbourhood, as well noting that political support for large-scale stabilising missions has declined strongly. Hybrid threats: War in the twilight zone Since the end of the Cold War NATO has expanded its remit at the initiative of its secretaries-general and individual member countries, moving into fields regarded as relevant to security. These include energy security, climate protection, and questions of equality, diversity and the role of women in conflicts. This has successively turned NATO into a multidimensional security organisation. Most of the think-tanks agree these issues will recede as The relevance of the southern dimension and the danger of conflict Figure 6 Germany United States Poland Finland Sweden Lithuania UK France Italy Netherlands Turkey Relevance residual relevant residual residual residual residual residual relevant dominant residual dominant Danger of conflict low medium low low low low low medium high low high dominant Relevance relevant residual high Danger of conflict medium low Threat perceptions and risks 11

collective defence comes back to the fore(not to mention the Trumpists’ militant aversion to“diversity, equity and inclusion”). Hybrid threats, on the other hand, are regarded as an acute security problem – and a grave threat in connection with the Ukraine war. They are attributed principally to Russia, but Chinese(and North Korean or Iranian) activities also feature. Relevant hybrid threats include disinformation, ­cyberattacks, sabotage and not least instrumentalisation of migration. There is broad consensus that NATO should be given responsibility for deterrence and defence against top-level hybrid threats: acts of sabotage and cyberattacks with the potential to cause great harm. There is less agreement on the less serious threats, namely, disinformation, cybersecurity and migration(affecting member countries to varying degrees). Here, according to the majority of the experts, principal responsibility for political and societal resilience lies with the member countries. NATO’s role would be to define standards for national resilience. In this, however, NATO competes with the EU, whose regulatory instruments make it more effective, also in the security realm. In 2016 NATO agreed that hybrid attacks could potentially invoke Article 5, although member countries and experts disagree on both the trigger and the expected deterrent ­effect. There are also isolated calls, in particular on the eastern flank, for NATO to conduct its own offensive hybrid ­operations. 12 Friedrich-Ebert-Stiftung e.V.

2 How to tackle the threats? Threat perceptions are one thing, defence readiness and strategies quite another. The discussion revolves around two basic questions. How much defence spending is enough to fund an adequate level of defence? And what military measures are required to credibly deter an attack and to back up the commitment to defend every square metre of Alliance territory? The debate has shifted a great deal since Donald Trump’s re-election in November 2024. The European NATO members are showing a much greater willingness to increase their defence spending. And they are starting to explore ways to compensate for the possible loss of American leadership, in both the conventional and nuclear spheres. Defence spending: How much is enough? The target of spending at least 2 per cent of GDP on de fence was reiterated in 2014 after the Russian annexation of Crimea and underlined again after Russia’s invasion of Ukraine in 2022. For two(rather contradictory) reasons this benchmark has been regarded as too low since Trump’s re-election the latest. One is that many European NATO members hope to keep the United States in Europe by ­acceding to Washington’s demands for higher European defence spending(burden sharing). The other is the need for higher spending as a precaution against Washington’s threats to wholly or partly end its military contributions to European defence. In policy research an even higher spending target is no longer ruled out. But the spectrum of opinions on its feasibility is very wide, both within and between the countries. There is a conspicuous gap between northeastern and southwestern Europe. Most of the northeastern members are already spending more than 2 per cent of GDP, and their think tanks all argue for a further increase. Most of the southwestern members still fall short of the 2 per cent target, with commentators there seeing little leeway for future increases. These differences result from the respective threat perceptions, which are determined by geographical location and historical experience. On a second axis, analysts who expect a prolonged conflict with Russia argue for high levels of spending, while those who see possibilities for reconciliation in the medium term advocate lower levels of spending. reale jährliche Differenzen [zum Vorjahr] in % Defence spending of European NATO members and Canada 20 16 Figure 7 17.9 12 9.3 8 5.9 4.2 4.7 4 3.0 3.6 3.7 1.6 2.5 0 –1.3 –0.9 –4 –2.7 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023e 2024e Notes: real annual change year on year, based on 2015 exchange rates. Figures for 2023 and 2024 are estimates. Source: NATO 2024 How to tackle the threats? 13

Defence spending as% of GDP in 2014 and 2024 Figure 8 Poland Estonia USA Latvia Greece Lithuania Finland Denmark UK Romania North Macedonia Norway Bulgaria Sweden Germany Hungary Czechia Turkey France Netherlands Albania Montenegro Slovakia Croatia Portugal Italy Canada Belgium Luxembourg Slovenia Spain 3.43 3,38 3.15 3.08 2.85 2.41 2.37 2.33 2.25 2.22 2.20 2.18 2.14 2.21 2.11 2.10 2.09 2.06 2.05 2.03 2.02 2.00 1.81 1.55 1.49 1.37 1.30 ← NATO guideline 2 % 1.29 1.29 1.28 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Notes: based on 2015 exchange rates. Figures for 2024 are estimates. Source: NATO 2024 2014 2024e 4.12 4.0 4.5 14 Friedrich-Ebert-Stiftung e.V.

Defence spending, projections for 2028/30 Figure 9 Lithuania Poland USA Germany France UK Finland Sweden Netherlands Turkey Italy 0 1.8 1.6 4.0 3.5 3.5 3.0 3.0 2.6 2.5 1 2 3 4 5.0 5 6.0 6 7 % of GDP Overall, willingness to increase defence spending has increased markedly. That is already reflected in NATO’s actual spending(see Figure 7; note that the figures for 2023 in clude new member Finland and for 2024 Sweden). It is clear that willingness to increase defence spending began to grow in 2023 and accelerated from the second half of 2024, with Donald Trump’s re-election and even more so with his subsequent foreign policy activities. By the end of 2024 NATO Secretary-General Mark Rutte was making his legendary call for spending“considerably north of 3%” (Rutte 2025a). More precisely, he was thinking of 3.6 per cent or 3.7 per cent of GDP:“If you don’t do that, take a course in Russian or go to New Zealand”(Rutte 2025b). Donald Trump went even further, demanding 5 per cent of GDP,“which is what it should have been years ago”(Trump 2025a), which in fact in the run-up to the NATO summit in June 2025 is about to become the new benchmark. 1 And a simulation conducted by the Brussels-based Bruegel Institute and the Kiel Institute for the World Economy calculated that a withdrawal of US forces alone would require the European NATO members to invest 3.5 per cent of their an nual GDP(250 billion euros annually) in the short term (Burilkov and Wolff 2025) – in addition to their regular planned defence spending. As the following figure shows, significant efforts have been made, but member countries have responded very differently(as of spring 2025). These figures are projections as of spring 2025, and as such not set in stone. Some member countries, namely Italy, France and Poland, are struggling with high levels of state debt that place question marks over their ability to realise these goals. They are therefore calling for multinational funding instruments modelled on the EU’s joint borrowing for the Covid recovery fund. In some cases the national targets are also vague. For example, the German coalition agreement between CDU/CSU and SPD merely states that there should be a clear and substantial increase in defence spending during the coming legislative period, with the level orientated on“NATO capability targets”(Koalitionsvereinbarung 2025: 130). 2 In April 2025, Trump and his secretary of defense announced a cool trillion dollars for defence in 1  Trump’s call apparently left such an impression that in May 2025 the NATO secretary-general also called for 5 per cent. A little creative accounting is involved though: actual defence spending should rise to 3.5 per cent of GDP, with the remaining 1.5 per cent accounted for by defence-related investment such as infrastructure; see ­Gutschker, 2025. 2  At the informal meeting of NATO-foreign ministers in Antalya on 14 May 2025, German Foreign Minister Johann Wadephul stated that this meant that Germany also ­supported Trump’s(and Rutte’s) demand for 5 per cent(Zeit Online 2025). However, despite partial suspension of the constitutional debt brake, it remains unclear how this is to be financed. How to tackle the threats? 15

the 2026 US budget(Trump 2025b). The situation is similarly vague elsewhere, especially in countries with coalition governments – although in all cases serious pushback comes only from the political margins. When considering these extremely ambitious targets we should remember – as the Washington Peterson Institute for International Economics notes in its analysis of global defence spending – that in 2023 only nine countries worldwide spent 5 per cent or more of their GDP on defence, among them Algeria, Armenia, Israel, Lebanon, Oman, Russia, Saudi Arabia and South Sudan, most of which are or have recently been at war; five of them are autocratic petro-states(Hendrix 2025). Conventional defence: capability gaps and dual risks NATO is again prioritising collective defence. Its regional defence plans – reintroduced for the first time since the end of the Cold War – lay out how it intends to defend every square metre of NATO territory. Instead of relying on asymmetrical deterrence by punishment, as it did post-2014, NATO is now pursuing deterrence by denial. Forward defence is to be realised by forward basing of NATO forces to support the national armed forces of the member countries on the northeastern flank, and by rapidly deployable reinforcements. This revival of conventional defence is supported by most of the think tanks in our sample of countries. Most commentators acknowledge the real expansion of conventional defence capabilities, compared to the period 2014 to 2022, but are critical of three aspects: Firstly, think tanks in many member countries doubt that the process of reconstituting Western military strength will be able to keep pace with the assumed trajectory of Russian rearmament. Russia, they say, has switched to a war economy capable of sustained, high-volume arms production, and now possesses large armed forces with combat experience. Therefore, Russia could be capable of attacking NATO within five to seven years at the latest. NATO is neither materially nor mentally ready for a long war of attrition. In light of the lessons of the Ukraine war, drones and drone defence, manpower, and munitions are identified as the key weaknesses of NATO forces. Secondly, realisation of the regional defence plans – and thus the forward defence capability – depends absolutely on the five rapidly deployable and combat-tested American brigades in Europe and the rapidly deployable up to 200,000 US reinforcements. It is unclear whether the re gional defence plans can be fulfilled at all without meaningful US contributions. Thirdly, because Russia has the interior line and can concentrate its forces more quickly than NATO, think tanks warn of the likelihood –despite the emphasis on forward defence – of rapid horizontal and even vertical escalation. One such scenario is a coup de main to cut off the Baltic states. Nuclear deterrence reloaded The deficiencies of conventional defence and Russia’s ­nuclear sabre-rattling before and during the Ukraine war once again underline the importance of nuclear deterrence. They also reveal how nuclear weapons can be employed as instruments of conflict management. Moreover, Donald Trump has left his European NATO partners in no illusion about their fundamental dependency on the United States and its nuclear shield. In this situation, discussions primarily point towards greater acceptance of nuclear deterrence and nuclear sharing within NATO. There is little support for joining the non-proliferation treaty today – not even in Germany. However, there are still differences of emphasis concerning the significance and risks of nuclear deterrence. Here again we see a northeast/southwest divide, but this time without Finland and Sweden, which maintain their stance of nuclear abstinence. Commentators in the states on the Alliance’s eastern borders believe that credible nuclear deterrence is essential and demand to be visibly included in NATO’s nuclear sharing. In Poland there is even talk of the country acquiring its own nuclear weapons(as in certain quarters in Germany). On the other hand, this question attracts little interest in the southwestern members, some of which are already included in nuclear sharing. Another debate revolves around the risks of nuclear de­ terrence. Before Trump’s re-election in November 2024, some observers felt that NATO’s deterrence strategy lacked credibility and argued for it to be modernised or adjusted. Proponents of this position argued for groundlaunched medium-range nuclear missiles to be deployed in Europe and for American nuclear weapons to be stored in Poland. Others saw inadequate crisis stability and an incipient arms race as the greater risks. But even for these critics, treaty-based arms control is inconceivable in the current situation. Instead, they argue for unilateral restrictions and stabilising measures. Finally, Trump’s re-election provoked a third debate, one that had already surfaced during his first term. How dependable is the American nuclear shield, and are there ­alternatives? Today faith in the US nuclear guarantee is even weaker than it was during Trump’s first term, even if some still cling to hopes that the United States will ­decide not to withdraw its nuclear umbrella despite the current transatlantic spats. However, the credibility of extended deterrence will rapidly unravel if the United States reinforces lack of interest in European security and affirms its unwillingness to share risks – for example by reducing its troop numbers. When it comes to alternatives, there is broad consensus that acquiring new European or national nuclear weapons are not a realistic option, even if it might appear prescient in some quarters. Instead, interest focusses on a possible European dimension of the French(and British) deterrent. 16 Friedrich-Ebert-Stiftung e.V.

The limitations, however, are obvious: the French deterrent is much smaller and less flexible, while France’s traditional deterrence philosophy sees nuclear weapons as a credible protection only for its own national territory. Scepticism weighs all the heavier in a situation where Russia is threatening to use nuclear weapons as an instrument of conflict management. Until the Munich Security Conference in February 2025, most experts believed NATO’s existing nuclear sharing arrangement to be virtually irreplaceable and advised against any thought of Europeanising the French deterrent. However, after Munich, in a context of growing doubts over reliance on Washington, there is growing support(even on the eastern flank) for the idea of actively exploring the option of using French(and British) nuclear weapons to create a European supplement to the American deterrent. How to tackle the threats? 17

3 Ukraine’s place in the European security architecture After Russia’s invasion of Ukraine in February 2022, NATO members mobilised enormous military support, unprecedented in scope and quality. That support has been stronger in eastern member countries than in the west but has been configured to avoid becoming an active party to the war. Even if Ukraine and NATO lack a credible war strategy – at the latest since the failed Ukrainian summer offensive of 2023 – Western politicians have clung to four articles of faith: Ukraine must win the war(or at least not lose it); support will be provided for“as long as it takes”; “nothing about Ukraine without Ukraine”; and the door to NATO remains open in principle. Until Donald Trump’s re-election only Turkey and Hungary deviated from that line(as well as Slovakia after the change of government at the end of 2023). Credible security guarantees for Ukraine are a central question, which already played a role in the talks between Ukraine and Russia in March and April 2022 in Istanbul. At that time bilateral security guarantees – in which the Kremlin insisted on participation and a veto – were discussed as part of a prospective peace agreement. Since then, the Ukrainian side has concentrated almost exclusively on joining NATO as the most – and only – credible guarantee. The perspective of membership had been suggested to Ukraine at the Bucharest NATO summit in 2008 (without a concrete timeframe) and was enshrined in the Ukrainian constitution in 2019. In advance of the NATO summit in Vilnius 2023 a majority of members indicated their support for Ukraine accession once the fighting has ended. However, on account of American(and German) Positions on NATO membership for Ukraine United Kingdom Poland Finland Lithuania France Sweden Netherlands Germany USA Italy Turkey Yes lean yes lean no Tendency Majority opinion Minority opinion 18 Friedrich-Ebert-Stiftung e.V. Figure 10 No

reservations the summit decisions went little further than the formula of 2008: Ukraine should be admitted but no concrete timeframe is named. NATO’s 2024 anniversary summit in Washington essentially confirmed that position. Here again we find conspicuous differences between and within the member states. The first of these follows the now familiar northeast/southwest pattern. Analysts in the northeastern countries all agree with their national politicians that Ukraine can only find security within NATO and should be permitted to join as soon as the war is over. Until November 2024 this position was also supported by most British and American and some German think tanks. French politicians and analysts were initially more cautious and were surprised by President Macron’s U-turn in advance of the 2023 NATO summit in Vilnius. A second difference lies between think tanks that believe that the Russian threat will be permanent and those that regard the confrontation as transient. The former argue hard for Ukraine to join NATO, though without being able to say how this can be achieved in the absence of military victory. The latter think that NATO membership would be too provocative and argue it would risk escalating the war and/or preventing its termination. After Trump and his secretary of defence threw out any prospect of Ukraine joining NATO and made it clear that Europe is now responsible for guaranteeing Ukraine’s security, there are essentially only two much less credible possibilities. Either to ensure that Ukraine can defend itself in future, or to support its security in some other way, if need be without the United States. The spectrum of ideas at play in the political and academic debate is broad, ranging from enhanced bilateral treaties or EU membership for Ukraine and a security force provided by a“coalition of the willing”, to the idea of extending Article 5 of the NATO Treaty to Ukraine without formal membership, which Rome has suggested. The idea of enabling Ukraine to defend itself – also discussed as the“Israel”,“hedgehog” or“porcupine” option is the least fraught for NATO, because it would stabilise Ukraine as the Alliance’s defence perimeter. The risk of NATO becoming directly embroiled would be under control – at the price, however, of greater risks(and costs) for Ukraine(which would essentially remain a proxy) and with greater risk of renewed war in Europe. This route would also suffer a symbolic political flaw, in that it would be tantamount to admitting that Russia had won the conflict over the central principle of freedom of choice. The idea of deploying peacekeeping troops(discussed as a“Reassurance Force”) without American participation(or with no more than symbolic backstopping) embodies the desire to ensure adequate deterrence at the heart of the protracted conflict between Russia and NATO. However, under NATO’s own deterrence philosophy, this would not be credible without Article 5 protection and would expose the participating forces to considerable danger. At the time of writing – six weeks after the initial summit in Paris at the end of March 2025 – enthusiasm for participating in such a force remains very lukewarm and the reception among experts is reserved. Critics doubt whether Europe would be able to provide the required forces(estimated at least five brigades totalling 25,000 to 30,000 troops) within the timeframe or they re ject the proposal on account to the level of risks involved. Here, however, the aforementioned northeast/southwest divide does not apply. The northeastern states are too small, too concentrated on their own territorial defence – or like Poland(and even more so Germany) too risk-averse. Instead, we observe a split between the nuclear-armed middle powers, which claim leadership, and the others. In view of the vagueness of the alternatives, most commentators currently regard the hedgehog option as the most realistic. Ukraine’s place in the European security architecture 19

4 Dealing with Trump: Transatlantic hopes and European visions Within a few days of Donald Trump taking office, it was obvious that the Alliance had been plunged from the heights of reinforced collective deterrence of Russia into a grave and potentially existential crisis. But for all the alarmism on this side of the Atlantic, and however unsettling we find Trump’s destructive activism, the material consequences of his erratic statements for NATO’s cohesion and ability to act remain unclear. Europe is consequently also undecided how to best respond: through meek conciliation or upright resistance. The same also applies to policy research. There is consensus about the fundamental challenge facing NATO. This applies both to the fundamental question of the future role of United States in the international system, and very directly to Washington’s current attitude to its allies. Five areas of conflict stand out. They are viewed very similarly across the European member countries(although Turkey deviates a little). These are: the possibility of the United States leaving NATO; a potential reduction of US forces in Europe; the Trump administration’s unilateralism; Trump’s tariff conflicts; and the territorial conflict alluded to by Trump regarding Greenland. What they all share in common is that the threat alone is set to destroy the trust that holds any alliance together and represents the precondition for credible promises of mutual assistance. Only deep mutual trust can neutralise the two core problems of any military alliance – abandonment by allies and entrapment in unwanted conflicts. Although the idea of leaving NATO has been repeatedly touted by Trump and his assistants, it is rather unlikely that the United States will actually do so. Legislation adopted by the US Congress in 2023 stipulates that such a decision requires approval by a two-thirds majority in the Senate. Although that is a formidable obstacle, there is little doubt that Trump could also end membership in practical terms without formally leaving. (Partial) withdrawal of US forces from Europe is a less unlikely prospect. Here the scope and justification would be relevant. Is the point of withdrawal to show greater force against China? Is it part of a unilateral deal with Russia, or is the threat of withdrawal a bargaining chip to extract concessions from Europe? And is it limited to the reinforcements deployed since 2014(and 2022) or will the cuts go further? No decision has been made to date, but there can be little doubt that the harm to NATO would be directly proportional to the type and size of withdrawal. Trump’s unilateralism is most relevant and most damaging for NATO in connection with his overtures to Russia – to end the war in Ukraine and more generally to revive cooperative relations with Russia. It makes a mockery of all the principles of a rules-based international order and sees the United States voting with a handful of rogue states in the United Nations. This has all come about unilaterally and impetuously without any consultation with Washington’s allies. The tariff conflict between Washington and Brussels has inflicted deliberate harm on the members of NATO and the EU – ostensibly to end EU’s supposed“exploitation” of the United States. There is broad consensus that the intensity of this conflict harms NATO’s coherence in two ways. For one thing, because Trump’s tariffs are transforming allies into adversaries and makes its military presence directly contingent on trade concessions. But also because the Trump administration might use trade talks as leverage to extract financial compensation for its protection, as it has already done with its Asian allies. The possibility of territorial conflict over Greenland is a nightmare for NATO. It is bad enough that the United States is openly pursuing the possibility of acquiring the territory against the will of NATO partner Denmark – and seeking to influence the territory’s citizens. If, however, the United States actually pursues annexation of allied territory“by all means possible” – as Trump has repeatedly insinuated – it would not only be violating the principles of international law that the West treats as sacrosanct(viz. Crimea and Donbas). Such an act would also explode the raison d’être of the military alliance, whose ultimate mission is to defend its members’ territory. This raises the longer-term question of the underlying parameters of Washington’s new foreign policy and America’s role in the international system. It is still conceivable that Trump will be a transient phenomenon, that he will be brought down by his incompetence and contradictions – as in his first term. But that is not likely and certainly not inevitable. On both sides of the Atlantic, realisation is dawning 20 Friedrich-Ebert-Stiftung e.V. Dealing with Trump: Transatlantic hopes and European visions

What future with the United States? Two options Lithuania Italy Poland Sweden Finland Germany United Kingdom Netherlands France Keep it up Majority opinion Tendency Minority opinion Figure 11 Europe first that Trump represents longer-term trends in US politics. Many factors drive the trend towards nationalist decoupling: spiralling socio-political tensions and societal fragmentation; sweeping deindustrialisation; a relative loss of international power; and the failed interventions of the“forever wars”. Given the geographical remoteness of the conflicts in Europe, the Middle East and the Far East, and the size of the US internal market, decoupling is a plausible option. From that perspective, it is no surprise if the Americans see the liberal international order as a“a maze of burdens and vulnerabilities”(Beckley 2025). And it is equally unsurprising if unilateralism and zero-sum thinking follow – in the worst case even imperialism and autocratic“great power collusion” carving up spheres of influence(Goddard 2025). Nevertheless, despite deepening conflicts and structural shifts in the political and societal foundations of US foreign policy, it is by no means inevitable that United States will actually withdraw from the Alliance. One reason to remain – which is shared among large parts of the Republican Party – is that NATO serves a string of rational US interests: → It provides a logistics hub for /US power projection. → It ensures influence in an economically and politically important region whose fate has significant implications for the United States. → It embodies sunk costs in the form of US military bases in Europe. → Leaving would incur domestic political costs – among the public, within the US security elites and among the Republicans in Congress(Pew 2024). →“NATO’s deterrence of Russia … is vital to the ability of the United States and its allies collectively to counter threats in other theaters”(Rand Corporation 2024). In a global conflict constellation characterised by a stable alliance of autocracies – China and Russia – directed against the United States, even Trump must surely perceive allies as assets rather than deadweight. Cozying up to Putin has done nothing to weaken the Moscow-Beijing axis. Dealing with Trump: Transatlantic hopes and European visions 21

We do not currently know whether the United States will withdraw most of its military forces from Europe, in line with the concept of a“dormant NATO”. But there can be no doubt that Trump’s actions tear up NATO’s shared values. Equally obviously he is dismantling America’s traditional leading role. It is unclear and contested, on the other hand, whether the transatlantic Alliance can survive solely on the basis of interests that are only partially shared. This confronts the European partners with the question of how to respond to Trump’s“America First” ideology. Should they continue to invest in a transatlantic NATO and keep the United States on board by offering compromises? Or should they start preparing for a US withdrawal by building European alternatives? The decision is complicated because unintended side-effects of both sides’ strategies could make disintegration inevitable. For example, any attempt by the United States to leverage its dominant position in NATO to extract concessions from its European allies risks being seen as decoupling and could motivate Europe to seek greater autonomy. Conversely, the twin-track strategy currently pursued by most European governments could also encourage US disengagement. For example, European efforts to tie the United States to NATO by offering to purchase American weapons are incompatible with the kind of precautionary measures that are advisable for the eventuality of the United States actually withdrawing. Specifically, such purchases would contradict any coherent strategy for strengthening Europe’s own defence industry. To date NATO’s Secretary-General, the European member countries and Canada have been exerting great effort – in the face of all the evidence – to preserve as much as possible of NATO in its existing transatlantic form for as long as possible. Their willingness to make compromises for the sake of keeping the United States on board is predicated in the first place on the external threat from Russia. But they are also aware of the difficulties of replacing US leadership and the risks involved in alternative security arrangements. Success is not guaranteed, and the European members are having to face up to the possibility that they may have to prepare for a US withdrawal. This discussion has only just begun. Opinions diverge within and between the member countries too, once again on account of east-west differences in threat perceptions, political traditions and the strength of feeling of belonging to Europe. One end of the spectrum is marked by the hope that it might still be possible to find an understanding based on shared interests and adjusted burden sharing. The other end believes that the transatlantic conflicts are so grave that a break is likely, and Europe will have to guarantee its own security without the United States. At the time of writing – early May 2025 – the outcome remains unknown. Which interests and trends ultimately come out on top will depend on multiple factors and their interactions that are currently impossible to predict. However, drawing on political and academic assessments, we can map out the possible and probable paths for a NATO facing the twin challenges – the external from Russia and the internal from Trump. 22 Friedrich-Ebert-Stiftung e.V.

5 The future of NATO: Three development paths Trapped between the acute external threat of Russia and the no less acute internal danger from the Washington, NATO is at a crossroads. Which path it chooses will depend on the answers to the three questions we began with: → Can Europe keep the United States on board? → Will European NATO members choose the path of ­European autonomy? → Or will NATO become a toolbox for changing“coalitions of the willing”? It is now virtually beyond doubt that Donald Trump will ­reduce US engagement in NATO. It remains unclear how far the retreat will go and what possibilities will remain for European security. It is also unclear how the transatlantic conflict has affected mutual trust. It will be crucial for the chances and risks of any future security arrangement how the centrifugal forces and blocking tendencies that exist within any intergovernmental security organisation are contained. Historically US leadership has performed that role and has been central to NATO’s cohesion and ability to act. That leadership rests on three pillars: material, ideational and institutional. Materially the United States keeps 100,000 troops stationed in Europe(five combat-ready ­brigades) as well as reinforcements based in the United States. It also provides complex and costly enablers such as reconnaissance and communications satellites – and not least the nuclear deterrent. It is upon this material foundation that the ideational acceptance of America’s leading role in Europe has rested over the decades. Finally, the United States also wields institutional power within NATO in the guise of the Supreme Allied Commander ­Europe(SACEUR). Even in times of peace, the SACEUR possesses wide-ranging powers to act autonomously, and these are even more robust in crisis and war. So even in the event of an impasse in the North Atlantic Council, the SACEUR would remain effective in his second function as Commander of US Forces in Europe, and willing European states could continue to place their forces under his command. Future European defence arrangements – whether within or outside NATO – will have to clarify whether and how these US contributions to European security can be preserved or replaced. We have identified three possible trajectories for NATO: the status quo, the organisation’s demise, or the middle way, as a framework for“coalitions of the willing”. These are predicated on the current contradictory constellation of an external threat bringing the partners together while the internal threat creates centrifugal forces. How this situation will develop cannot be predicted in any detail, but we can identify the trends and their drivers. In view of the dual threat of Russian imperialism and American nationalism it is clear that NATO cannot remain as it was. The questions about the Alliance’s functional and geographical scope may have been sidelined since February 2022, but they have not gone away. They have merely been crowded out by the more pressing question of the future institutional shape of European defence: How to organise European security and collective defence with a markedly reduced US presence or none at all? The three potential paths can be summed up as simulation models that allow us to assess the benefits and risks of the respective security arrangements: A transatlantic NATO minus The United States remains a member of the Alliance and retains reduced forces in Europe, while European NATO members assume considerably more of the burden and take responsibility for their own security. A European defence union The United States leaves NATO and the European members organise their own defence. Here the European Union could replace NATO, but there would be other alternatives. The crux of this option would be an integration mechanism to prevent impasses by introducing majority voting. NATO as toolbox The United States remains in NATO, but in a non-hege­ monic role with a markedly reduced presence in Europe. NATO permits the formation of ad hoc coalitions of states with similar interests and objectives under its auspices. In those cases responsibility for deployment of forces remains with the respective states. Impasses are prevented by forming coalitions, with a shared understanding that these are also able to draw on NATO’s resources. Dealing with Trump: Transatlantic hopes and European visions 23

All three models are conceivable under current circumstances. But they each possess strengths and weaknesses that make their realisation more or less likely. The assessments laid out below focus on the core question of securing cohesion and ability to act, whether in NATO or some other defence arrangement. The transatlantic NATO minus model assumes that in spite of the erosion of shared values shared interests remain the foundation of cooperation, and suffice to uphold the transatlantic NATO. The Europeans keep the United States involved in western Europe’s security through concessions like higher defence spending and increased arms purchases. The United States remains present in Europe but reduces the additional forces built up since 2014 – ­especially on the eastern flank – and leaves the main responsibility for conventional defence(and for Ukraine’s ­security) to the Europeans. From the perspective of European NATO members this model offers significant opportunities. Security can still be guaranteed at acceptable cost. The Europeans do not have to ­replace all US forces and can hope that the Americans will continue to provide access to crucial enablers. The ­nuclear shield would also nominally remain. For all the opportunities, considerable risks would be involved. If Washington’s interest is so weak that it has very few troops still committed to Europe’s forward conventional defence – or none at all – then the nuclear deterrent loses its credibility even if Washington does not explicitly withdraw it. The credibility of traditional US leadership would also decline, even if Washington continues to claim it. It is already in doubt on account of the political conflicts with the Trump administration. Without a material basis it would collapse. The institutional pillar of US leadership would also be lost under these premises. Without meaningful numbers of US troops under his command, an American SACEUR loses legitimacy and the ability to act autonomously. In light of these risks, further negative implications of this model gain greater relevance from the European perspective. That could apply for example to the Europeans’ reactions to their threat assessments, which would still be shaped by the US presence in the Alliance. And it would compromise Europe’s defence industry autonomy if that presence had to be bought through arms purchases from the United States. In short, the transatlantic NATO minus model would be fragile, in spite of complementary interests. The countermodel is the European defence union without the United States. It is based on the assumption that deeper integration is the only option for ensuring coherence and ability to act, without hegemonic leadership. An in­ tegrated European solution does not necessarily mean the European Union replacing NATO. Instead, it is more about introducing decision-making procedures that secure cohesion and prevent impasses. Because the states remain sovereign that means overcoming the veto principle by introducing majority voting. Such a procedural change would have to be backed up by delegating powers to supra-state organs such as a European SACEUR, as well as forms of defence industry cooperation that restrict national autonomy. The model’s advantages are obvious. It enhances awareness that Europe is responsible for its own security. Introducing majority voting would preserve the ability of the EU states(or the European NATO members plus Canada) to act coherently despite their disparate perspectives and interests. Integrated forms of defence industry cooperation would enable cheaper and more efficient procurement, including costly enablers that would need to be operated collectively. Joint arms production and procurement could pave the way for deeper defence integration. Of course, arms production cannot be compared to civil manufacturing, and states seek to retain control over their arms industries for reasons of sovereignty. But the external threat mitigates towards efficiency over sovereignty, and that entails collective European arms cooperation and procurement. However, the costs would also be considerable, in two senses. The Brussels-based Bruegel Institute and the Kiel Institute for the World Economy calculated that securing Europe’s collective autonomy require annual investment of at least 250 billion euros(or 3.5 per cent of GDP) in the short term(Burilkov und Wolff 2025) – in addition to regu lar planned defence spending. On top of this there would be high costs of sovereignty. Integrated armed forces require clear and decisive political authority – and that means letting go of key elements of national sovereignty. No European state has to date shown the slightest willingness to accept such costs. The degree of scepticism towards integrated security concepts and a European army – even in rhetorically integration-friendly Germany – indicates that European states are not yet ready for such a move. Even if it were possible to transfer responsibility for security to a supranational organ, this would be a bureaucratic actor akin to the EU Commission with restricted agency in defence matters. The problems become obvious if one tries to imagine how an integrated ­uropean nuclear deterrent would look and function. The concept of NATO as toolbox assumes that the United States remains within NATO but only retains a partial presence in Europe and no longer exercises leadership. Under this model the European NATO members cooperate closely but without surrendering national authority over matters of war and peace, including all military deployments. This secures ability to act and avoids impasses by creating ad hoc coalitions of states with similar interests under the aus­ pices of NATO. For a string of practical reasons NATO offers a better in­ stitutional framework for such cooperation than the EU. NATO possesses important resources such as its integrated command structure, established procedures for joint defence planning, a calendar of exercises to improve coopera24 Friedrich-Ebert-Stiftung e.V.

Locating the debate in the three models Figure 12 France United Kingdom Poland Finland Lithuania Sweden Netherlands Germany Italy USA Turkey NATO as toolbox Majority opinion Transatlantic NATO minus Tendency European defence union Minority opinion tion between national forces, procedures for promoting interoperability, and shared military assets like the AWACS fleet. All these can be used without the United States. Additionally, it would be easier to integrate the United Kingdom, Canada and Turkey outside the EU framework. The NATO members would be able to plan their collective defence on the basis of shared interests. NATO also has a tradition of more flexible options that originate in the discussions around the“Berlin plus” arrangements in the early 2000s and are manifested in the Framework Nations Con cepts, as well as experience with opt-outs and opt-ins:“coalitions of the willing” using NATO command structures as during the second phase of the Libya intervention in 2011. Problems would arise with this model if the situational shared interests no longer existed. As mentioned above, defence institutions find themselves confronted with specific problems concerning cooperation, such as“burden-sharing”,“buck-passing”,“balancing versus bandwagoning” and “abandonment versus entrapment”. Alliances without hege­ monic leadership find it harder to resolve such issues than the NATO as we know it. The role of the SACEUR is also almost impossible to substitute. Additionally, a NATO without hegemonic leadership would respond more slowly and less decisively to challenges, compared to the old NATO in which the superpower was able to short-circuit slow collective decision-making by forging ahead on its own. Finally, heterogeneity would come with the risk of reopening intra-­ European security dilemmas, for example through misunderstandings among partners or uncertainty over future willingness to cooperate. The openness, transparency and predictability of democratic states means that inter-democracy cooperation is more robust than cooperation between authoritarian states – although no guarantee. The models presented are ideals, and we have scrutinised them solely from the perspective of coherence and ability to act. The reality is usually more complex. That also applies to the many different ideas introduced to the debate since early 2025. Some proposals combine elements of the second and third models: the introduction of majority voting in a permanent coalition of states with similar perspectives and a similar level of ambition(Ischinger 2025). Oth ers combine elements of all three models by essentially Dealing with Trump: Transatlantic hopes and European visions 25

preserving the transatlantic NATO while exploring fall-back options in the form of European arms industry and/or defence integration, or closer cooperation in coalitions. For all the doubts and uncertainties, most European states in our study and their experts remain demonstratively faithful to the transatlantic NATO under American leadership. Most experts in the United States share this vision. This attitude is explained by political path dependency as well as the costs and risks of alternative models; in view of the Russian threat the latter weighs especially heavily. Only France, behind its reassuring force de frappe is(again!) pressing for greater emancipation from the United States. Support for the transatlantic NATO is especially pronounced in northern and eastern Europe. But it also remains the dominant attitude in Germany, at least in the political sphere. It implies a hope that it might be possible to stabilise the transatlantic NATO through deals that are at least tolerable or just to sit out the time until the US midterm elections in autumn 2026(or even the next presidential elec tion in 2028). But even in countries like Poland this goes hand in hand with support for stronger European involvement in defence policy and the defence industries. However they turn out, it is foreseeable that the coming changes in NATO will be very costly for its European members. That was ultimately decided in Moscow. But the shape of change will be largely decided in Washington. References Beckley, M.(2025). The Age of American Unilateralism: How a Rogue Superpower Will Remake the Global Order. Foreign Affairs, 16 April 2025. www.foreignaffairs. com/united-states/age-american-unilateralism(accessed 10 May 2025). Burilkov, A.& Wolff, G. B.(2025). Defending Europe without the US: First Estimates of What Is Needed, 21 February 2025. www.bruegel.org/analysis/defending-europe-­ without-us-first-estimates-what-needed(accessed 10 May 2025). Dembinski, M.& Fehl, C.(eds.)(2021). Atlantische Zukünfte: Eine vergleichende Analyse nationaler Debatten über die Reform der NATO. Berlin: Friedrich-Ebert-Stiftung. Goddard, S. E.(2025). The Rise and Fall of Great-Power Competition: Trump’s New Spheres of Influence. Foreign Affairs, 22 April 2025. www.foreignaffairs.com/united-­ states/rise-and-fall-great-power-competition(accessed 10 May 2025). Gutschker, T.(2025). Die NATO ringt um Ausgaben von fünf Prozent. Frankfurter Allgemeine Zeitung, 12 May 2025. www.faz.net/aktuell/politik/ausland/nato-verhandelt-u­ eberverteidigungsausgaben-von-fuenf-prozent-110471971.html(accessed 15 May 2025). Hendrix, C. S.(2025). Trump’s Five Percent Doctrine and NATO Defense Spending, 5 February 2025. www.piie.com/blogs/realtime-economics/2025/trumps-five-percent-doctrine-and-nato-defense-spending(accessed 10. May 2025). Ischinger, I.(2025). Europe’s Moment of Truth: The Transatlantic Alliance Is Under Grave Threat – But Not Yet Doomed. Foreign Affairs, 2 March 2025. www.foreign affairs.com/ukraine/volodymyr-zelensky-trump-europes-moment-truth(accessed 10 May 2025). Koalitionsvereinbarung(2025). Verantwortung für Deutschland: Koalitionsvertrag zwischen CDU, CSU und SPD, 21. Legislaturperiode. NATO(2024). Defence Expenditure of NATO Countries(2014–2024). www.nato.int/ nato_static_fl2014/assets/pdf/2024/6/pdf/240617-def-exp-2024-en.pdf(accessed 10 May 2025). Pew Research Center(2024). Growing Partisan Divisions Over NATO and Ukraine, 8 May 2024. www.pewresearch.org/wp-content/uploads/sites/20/2024/05/pg_2024. 05.08_russia-nato_report.pdf(accessed 10 May 2025). Rand Corporation(2024). Commission on the National Defense Strategy. www.rand. org/content/dam/rand/pubs/misc/MSA3057-4/RAND_MSA3057-4.pdf(accessed 10 May 2025). Rutte, M.(2025a). Pre-ministerial press conference by NATO Secretary General Mark Rutte ahead of the meetings of NATO Ministers of Foreign Affairs, 2 April 2025. www.nato.int/cps/en/natohq/opinions_234072.htm(accessed 10 May 2025). Rutte, M.(2025b). Rutte tells Europe: Invest in defense or learn Russian, 15 January 2025. https://europeannewsroom.com/rutte-tells-europe-invest-in-defense-or-learnrussian(accessed 10 May 2025). Trump, D.(2025a). Trump at Davos: NATO 5% push, tariff warnings for Europe. www.euronews.com/business/2025/01/23/trump-at-davos-nato-5-push-tariff-warningsfor-europe(accessed 10 May 2025). Trump(2025b). Trump, Hegseth promise record$1 trillion Pentagon budget. Politico, April 2025. www.politico.com/news/2025/04/07/hegseth-trump-1-trillion-defensebudget-00007147(accessed 10 May 2025). Zeit Online(2025). Außenminister Wadephul unterstützt US-Forderung für Militärausgaben, 15 May. www.zeit.de/politik/ausland/2025-05/wadephul-unter­stuetzttrumps-fuenf-prozent-plan-fuer-militaerausgaben(accessed 15 May 2025). 26 Friedrich-Ebert-Stiftung e.V.

Overview of the study series NATO’s Uncertain Future Matthias Dembinski and Hans-Joachim Spanger The Future of NATO – Country Report Poland Hans-Joachim Spanger The Future of NATO – Inside NATO Uncertain leadership in turbulent times: How the North Atlantic organization sees NATO’s future Matthias Dembinski and Hans-Joachim Spanger The Future of NATO – Country Report Germany Germany’s NATO Policy Shaped by the Ukraine War and Donald Trump Matthias Dembinski and Hans-Joachim Spanger The Future of NATO – Country Report Netherlands Wolfgang Wagner The Future of NATO – Country Report Russia Russian Views on NATO Hans-Joachim Spanger The Future of NATO – Country Report Italy A Committed but Divided Ally Elio Calcagno The Future of NATO – Country Report France France’s Pivot to Europe Barbara Kunz Overview of the study series 27

The Future of NATO – Country Report United Kingdom Leading the Euro-centric turn in NATO Gry Thomasen The Future of NATO – Country Report China Chinese Views on NATO: Global Opponent to a Rising China Pascal Abb The Future of NATO – Country Report Ukraine The‘Only Real Security Guarantee’? Ukraine and NATO Mikhail A. Polianskii The Future of NATO – Country Report Turkey Strategische Ambivalenz: Die komplexe Rolle der Türkei in der Entwicklung der NATO Hürcan Aslı Aksoy The Future of NATO – Country Report Sweden Sweden in NATO: ‘Reliable, Loyal and Engaged’ Adrian Hyde-Price The Future of NATO – Country Report Finland Preparing for the Worst Joel Linnainmäki The Future of NATO – Country Report Lithuania Lithuania as a pacesetter in terms of defense, determination and defiance against Russia Adam Roževič The Future of NATO – Country Report USA From Benign Leader to‘Uncle Sucker’: The US Debate on NATO Marco Overhaus You can find all studies for download and further information on this website: www.fes.de/en/future-of-nato 28 Friedrich-Ebert-Stiftung e.V.

About the authors Dr. Matthias Dembinski is an Associated Fellow in the ­Research Department International Institutions. His ­research interests are questions of justice in international relations, regional security organizations and humanitarian interventions. His regional focus is Western Europe. Dr. Hans-Joachim Spanger has been an Associate Fellow in Research Department Intrastate Conflict since 2019. His research focuses on European security, democracy ­promotion and Russia. Previously he held the positions of Head of Research Department Information and Knowledge Transfer at PRIF and Head of Research Department ­Governance and Societal Peace at PRIF.

NATO’s Uncertain Future NATO has been a key security pillar of German and European defence policy from the very outset. Since the end of the Cold War, however, it has undergone a series of international transformations and realignments, driven by developments in the global security environment and pressure from its own member states. While the Russian war of aggression against Ukraine has strengthened NATO’s self-perception as a key guarantor of collective security, the change in US administration at the beginning of 2025 raises fundamental questions once again. What role will the US play in Europe’s future security, and how might European nations respond to the situation? This publication is part of a Friedrich-Ebert-Stiftung study entitled“The Future of NATO”, which summarises and analyses the ongoing debates on the Alliance and current security challenges in 11 member and 4 non-member states. These country studies form the basis of an overarching publication which seeks to provide possible answers to the unresolved questions and propose potential scenarios for the future of NATO. Further information on the topic can be found here: ↗ fes.de