The Future of the Euro-Atlantic Security Architecture

The post-1945 Euro-Atlantic security architecture (EASA) – the layered patchwork of organisations, treaties, agreements and norms that have upheld European security for 80 years – is being fundamentally restructured. Many of the shifts are deep rooted, with Russia’s 2022 full-scale invasion of Ukraine currently driving this transformation.

A confluence of external and internal dynamics now amounts to the most acute challenge to the EASA since its inception and will influence how the future EASA develops.

1. The rules-based international order has been actively dismissed by revisionist powers and weakened through perceived hypocrisy of its Western advocates.
    
2. US leadership that upholds the EASA is no longer assured as the second President Donald J Trump administration dramatically realigns towards domestic priorities and the rise of China in the Indo-Pacific.
    
3. The intensification of great power competition is driving states to unshackle the constraints of multilateralism and wield their power to redefine international security.
    
4. Russia and China are deepening their partnership alongside their cooperation with Iran and the Democratic People’s Republic of North Korea – a grouping labelled ‘CRINK’ – to reshape the global order to their worldview and develop greater security linkages between the Euro-Atlantic and Indo-Pacific. Indeed, China’s President Xi Jinping views the current conditions in the Euro-Atlantic relationship as an opportunity for a greater leadership role of aligned ‘middle-ground’ powers.
    
5. The stasis of liberalism and the rise of populism within Europe and the US are creating unprecedented and simultaneous internal political instability, fraying Western unity and multilateral collective action.

Structure and Methodology

The purpose of this paper is to examine these dynamics, which are having an impact on the current and future EASA, and to develop recommendations for European states to shape the EASA to their strategic advantage. The central hypothesis is that the EASA is at an inflection point, with intensifying strategic competition and the emergence of new forms of security cooperation and military alliances rewriting the international rulebook.

This paper argues that the central tenets of the legacy EASA are not designed to deal with a more confident and aggressive Russia, the erosion of the rules-based international order and multilateralism, and the scepticism of the US regarding its future security commitment to Europe. Therefore, Europe must critically reassess which EASA elements remain fit for purpose, which parts need to be rethought and which are no longer capable of providing security.

The paper further argues that for European states to simply reaffirm existing principles and commitments – which Russia is actively seeking to destroy – is insufficient and exposes Europe’s impotence in global security. Without collective active engagement from European states on rethinking the future of EASA, there is a risk that Europe will fail to manage this transformational moment and fall behind strategically – only able to react to world events, rather than shape them. For Europe to have the time and space to rearm and transition between an old and new EASA, credible deterrence is imperative.

The paper addresses three research questions, from which recommendations are developed for European policymakers to strengthen the future EASA:

1. How might the EASA need to evolve to meet emerging and future security challenges?
    
2. What should be the priority objectives to transition to a future EASA and how can Europe best achieve them?
    
3. What role should the UK have in the future EASA?

The term ‘Euro-Atlantic security architecture’ can be understood in different ways. As the scope of this paper examines how Europe needs to structure and organise its security in response to shifting US priorities, ‘Euro-Atlantic’ rather than ‘European’ is used. In turn, ‘Euro-Atlantic security architecture’ refers to those organisations (NATO, the EU, the OSCE), frameworks (minilateral security arrangements), treaties and agreements (principally between the US, Europe and Russia) and norms (sovereignty and refraining from the threat or use of force) that aim to uphold European security. Europeans widely recognise that they must individually and collectively step up in providing for their own security, but there is little consensus on how best to do so considering the current political and economic constraints. 

This paper is part of RUSI’s ‘Future Euro-Atlantic Security Architecture’ project, sponsored by the Foreign, Commonwealth & Development Office’s Strategic Stability Programme. The research was conducted between April and October 2025 and is based on three types of sources: an expert-led conference hosted by RUSI on 15–16 July 2025, attended by Euro-Atlantic policymakers and experts; a series of semi-structured consultations with experts from UK and European Allied countries; and building on desk-based research of primary and secondary sources.

Ongoing work under this project, including research roundtables, will examine the role of nuclear weapons in the future EASA and the UK’s role in the security architecture of Northern Europe. Upcoming RUSI papers will address these questions in greater detail.

The EASA’s Changing Dynamics 

The EASA has managed to withstand 80 years of pressure and has adapted to changes in the security environment. At the multilateral level, NATO, the EU and the OSCE have demonstrated stamina, and demands for their protection has enlarged each organisation. However, new challenges of multilateralism have driven political expediency for more flexible minilateral formats – binding members through regional or thematic agendas – resulting in an unwieldly layered patchwork of arrangements. 

In addition, the formation of new global military partnerships and models of security cooperation are challenging the EASA’s relevance and existence and intensifying strategic competition. For Europe, it is therefore critical to understand the strategic significance of the challenge to conceptualise a resilient EASA that enables strategic advantage. Four fundamental structural shifts – Russian aggression, the rise of China, an unpredictable US and European political instability – have coalesced to create the most acute security crisis in Europe since 1945. These shifts indicate that a return to a pre-2022 EASA is not a realistic or desirable objective for the future.

Russian Aggression

The primary crisis for the EASA is Russia’s expanding aggression across Europe. The 2008 Russian invasion of Georgia and 2014 annexation of Crimea chipped away at the EASA, but the 2022 full-scale invasion of Ukraine was a violent attempt to overthrow and replace it. The December 2021 Russian Federation Draft Treaties, presented to both the US and NATO (and communicated initially through the 2009 Medvedev draft European Security Treaty) demanded that the fundamental principles underpinning the EASA – a respect for sovereignty, refraining from the use of force and the peaceful settlement of disputes – be revised, to instead be based on military might and spheres of influence as key organising principles. Such demands – including reversing NATO to its pre-1997 borders – were obviously unacceptable to the US and Europe; however, their outright rejection lent Moscow a partial pretext for the invasion. 

The current Russian position on negotiations over the war in Ukraine go far beyond the war and seek to achieve a broader deal on European security with the US, which was the original intent behind the 2021 draft treaties. President Vladimir Putin’s vision is brutally imperial: to establish and lead a ‘Union State’ comprising both Belarus (‘White Russia’) and Ukraine (‘Little Russia’ – a historically imperial term, which many Ukrainians find offensive and which Putin deliberately uses regularly) that would extend Russian power and influence across Europe. In November 2021, Russia signed a new security doctrine with Belarus to solidify the relationship, which removed the latter’s neutrality commitment along with barriers to Belarus hosting Russia’s nuclear weapons. Putin’s attempt to bring Ukraine into the fold has failed.

Therefore, Russia’s 2022 invasion not only shattered the European understanding of the EASA, but also devastated Putin’s own imperial vision, as it failed to subjugate Ukraine in 10 days (as was expected at the time). Indeed, Russia and Ukraine’s future visions of the EASA are fundamentally incompatible. At the time of writing, these rival visions are competing for Trump’s approval through the formation of the draft 28-point US–Russia Ukraine peace plan and the European counter-proposal. For both the Russian regime and Ukraine, the war is existential, and so the future of Ukraine is now central, rather than peripheral, to Euro-Atlantic security. Ukraine is firmly on the path to European integration, but Putin needs to conquer Ukraine to realise his imperial vision. In this sense, the political future of the EASA is being fought at the tactical level between Ukraine and Russia and will develop from the ashes of the war. 

A Weakened Russia

Three years on from the invasion – with over 1 million Russian soldiers believed to be killed or wounded – there is no indication that Putin’s intent has changed and he has in fact weakened Russia in four areas.

NATO always assumed Russia’s conventional military inferiority, but the extent of its failures advancing into Ukraine – before Western partners flooded Kyiv with military assistance – revealed the rot at the core of Moscow’s war machine. In turn, apparent Russian appreciation of its own conventional inferiority has probably led to a greater reliance on its nuclear arsenal for deterrence and, potentially, for war termination. Russia’s 2024 revision of its declaratory nuclear doctrine expanded the declared circumstances under which Moscow would consider the use of nuclear weapons. Consistent and thinly-veiled nuclear threats from Moscow – aimed at deterring greater Western support for Ukraine – illustrate the extent to which they have been relied on by Moscow due to Russia’s weakened conventional military capabilities. Combined with the disintegration of arms control arrangements between Russia and the US, these dynamics create nuclear escalation risks and may incentivise arms races in the conventional as well as nuclear space. 

Russia’s brutality has given NATO a new ‘lease of life’ since NATO withdrew from Afghanistan in 2021. The Alliance now has an undisputed enemy, welcomed two new members – Finland and Sweden – and spurred immense increases in defence expenditure for its members.

Russia has all but lost Europe as an oil and gas customer, compelling it to sell its products to markets in China and India at lower prices, which in turn is driving new forms of cooperation.

Russia’s full-scale invasion of Ukraine unmasked Putin’s true intentions in the eyes of Europe and reduced the international community’s already limited trust and confidence that Russia’s actions can be bound by the international norms and behaviours required to achieve strategic stability. From 2014 to 2022, Putin violated or suspended Russia’s participation in over 400 international treaties and conventions – including the 1994 Budapest Memorandum – breached constraints on conventional military capabilities, such as the Treaty on Conventional Armed Forces in Europe, and has breached or suspended compliance with nuclear arms control agreements, such as the Intermediate Nuclear Forces (INF) Treaty and the New Strategic Arms Reduction Treaty (New START). Russia’s transgressions even included breaches of the 1993 Chemical Weapons Convention, by deploying chemical weapons in Ukraine, and causing the deaths of two British nationals in 2006 and 2018 in radiological attacks against the UK, followed by cyberattacks against the Organisation for the Prohibition of Chemical Weapons (OPCW) itself.

Therefore, without fundamental political reform in Russia and the reversal of the trends outlined above, a return to the pre-2022 EASA is highly unlikely and – from a European standpoint – undesirable. Europeans simply cannot trust Putin or Russia to stick to any agreement designed to achieve strategic stability, and building an EASA against Russia will be crucial for maintaining European cohesion and public support for consistently higher levels of defence spending.

The Rise of China

The rise of China will impact the EASA structurally, as Beijing is partly driving the US to reassess its priorities. The 2022 US National Defence Strategy identified China as the ‘pacing challenge’ which is driving the US strategic deprioritisation of Europe. In his first speech in Europe in February 2025, US Defense Secretary Pete Hegseth declared: ‘The U.S. is prioritizing deterring war with China in the Pacific, recognizing the reality of scarcity, and making the resourcing tradeoffs to ensure deterrence does not fail’. Quantitative and qualitative advances in the Chinese nuclear arsenal add to concerns over China’s future posture in the Indo-Pacific and globally. The US – historically used to having to deter a single nuclear peer adversary – is now having to consider whether its conventional and nuclear capabilities and posture are fit for purpose to deter two advanced nuclear states.

Yet, China is not only a challenge in the Indo-Pacific, but has also been gradually building influence within the Euro-Atlantic. It has backed the ‘Friends for Peace’ in Ukraine group at the UN, is a significant investor in science and dual-use technology research on the Norwegian island of Svalbard and has long conducted foreign policy outreach in Central, Eastern and Southern Europe through the ‘17+1’ initiative. China has deepened all these activities since 2022.

At the same time, China is increasingly supporting Russia’s direct challenge to the EASA, with NATO labelling China a ‘decisive enabler’ of Russia’s war against Ukraine. There are indications that Russia is reciprocating by offering technical military support to China, training and equipping China’s People’s Liberation Army to build its capability to seize Taiwan. 

China is also becoming more overt in its global leadership aspirations, as the US retreats. In September 2025, China hosted the Shanghai Cooperation Organisation, where Xi took a thinly-veiled aim at Trump, telling assembled leaders that their countries must ‘oppose the Cold War mentality, bloc confrontation and bullying practices’. This was directly followed by a Beijing military parade, which was domestically presented as a ‘victory parade’ to commemorate the Second World War, but was a clear demonstration of China’s technologically advanced hard power, shaping a future to China’s advantage and posing a challenge to the US-led international system. That Putin and North Korea’s President Kim Jong Un were in attendance – up to 15,000 North Korean troops are thought to have fought for Russia against Ukraine – alongside India’s Prime Minister Narendra Modi, demonstrates the deepening connections between Euro-Atlantic and Indo-Pacific security. It also illustrates how military technical support between these powers is becoming overt and normalised, including India participating in the 2025 Russo-Belarus Zapad exercise.

Russia’s relationship with China and other global powers is helping Putin’s international rehabilitation. However, most concerning for Europeans is that Trump has accelerated this rehabilitation through the bilateral summit held with Putin in Alaska by creating a perceived equivalence between the two presidents that Putin has long coveted and will seek to amplify internationally. Putin now believes he can get back to the ‘main table’, and the initial US–Russia draft 28-point peace plan for Ukraine – and the European counter-proposal – contain measures to further this move, including inviting Russia back into the G8 (the G7 has developed a significant pro-Ukraine security dimension since 2022). The US push for Russia’s structural and institutional rehabilitation will severely impact the EASA and is likely to cause significant transatlantic divisions as Europe seeks to maintain maximum pressure on Russia.

An Unpredictable US

The US is becoming a less predictable and dependable ally for Europe and there are doubts regarding whether the US values alliances in the same way as during the Cold War. This is creating a critical leadership vacuum within the EASA. The new US National Security Strategy decisively prioritises protecting the homeland and Western Hemisphere above competition with China or Russia, in a significant departure from the strategy of the first Trump administration. Most worryingly for Europeans, the US seeks to reestablish strategic stability with Russia and intends to deal with the continent as a ‘group of aligned sovereign nations’, rather than through multilateral organisations, which is the preference for Europe on security policy. Europe can therefore assume that the US will be strategically distracted for some time, and that China and Russia will seek to exploit the resulting gap.

The uncomfortable truth for European states is that they have long outsourced their defence and security leadership to the US. In 2011, then-US Defense Secretary Robert Gates warned that the US Congress and taxpayers would lose their ‘appetite and patience’ for defending allies that are unwilling to defend themselves. This fed the clear disdain for NATO exhibited by Trump and his key national security officials. In turn, Trump’s ‘trade war’, which targeted Europe, actively undermines NATO’s Article 2 and its commitment for ‘Parties … to eliminate conflict in their international economic policies and … encourage economic collaboration between any or all of them’. US direct confrontation with both Canada and Greenland has caused further dismay within NATO. The most significant announcement at the 2025 Hague Summit was that NATO reaffirmed Article 5, demonstrating the fragility of the EASA.

While European actors rightly have little faith in Russia sticking with agreements, they also harbour doubts about the US standing by international agreements. Trump’s 2025 UN General Assembly speech revealed his worldview and his disdain for multilateral institutions. Moreover, sea changes in policy between Republican and Democratic administrations have had an impact on both the Paris Climate Accord and the Joint Comprehensive Plan of Action, designed to halt the Iranian enrichment programme, demonstrating the significant diplomatic challenges that Europe faces in keeping the US onside.

While the US is not expected to decrease its nuclear commitments to Europe, the expectation that the US will undertake a conventional draw-down on the continent will have knock-on effects on the credibility of US extended nuclear deterrence on the continent. A withdrawal of – or unwillingness to engage in – conventional capabilities in defence of Europe will create destabilising gaps in Europe’s escalatory options and key defensive capabilities – for instance, integrated air and missile defence (IAMD). At the same time, retrenchment from Europe in the conventional space sends a signal to adversaries and allies alike that the US is deprioritising European security, which risks exacerbating anxieties among European allies over the credibility of the US nuclear deterrent as well. This places additional demands on Europe’s two nuclear states – the UK and France – to consider whether and how their nuclear capabilities can help address possible emerging gaps, as well as on the rest of European NATO to address gaps in key conventional enablers for effective nuclear deterrence.

European Political Instability

European political instability is forcing European governments to focus on domestic challenges as international security dangers mount. The rise of populism and electoral gains from both far-right and far-left parties across Europe is straining unity and making it harder to manage multilateral security institutions. An increase in ‘spoiler countries’, such as Hungary, which can exploit the requirement of unanimity in both the EU and NATO to their advantage, is preventing strong collective multilateral action. Moreover, domestic political concerns, principally over immigration, are driving a distrust of international organisations and agreements, such as the European Convention on Human Rights (ECHR), which constitutes a central part of the current values-based EASA. Reform – the party currently leading the polls in the UK – and the Conservative Party are both campaigning to withdraw from the ECHR. If the UK voluntarily left the Council of Europe, it would be outside the organisation, alongside Russia and Belarus who were expelled, and this would impact the values-based nature of the agreement. Large states such as France – which has now had six prime ministers in 22 months – are consumed by domestic permacrisis, with little political capital to decisively influence international agendas and thus weakening Europe's unity.

Optimism

The above strategic shifts paint a bleak picture for Europe, but there are six reasons for optimism. 

Europeans Understand the Need for a New EASA

European political leaders understand the scale of the crisis and are committing more attention, resources and strategic thinking to manage it. The UK’s 2021 Integrated Review was an early formalisation of the view that a ‘defence of the status quo is no longer sufficient for the decade ahead’, while the EU’s 2025 Strategic Foresight report concludes that: ‘The EU should actively and with a coherent approach shape the discussion about a new rule-based global order and a reform of multilateralism’, creating post-Brexit UK–EU consensus. 

Public Support for Deepening European Defence

European societies are more supportive of a deepened defence union than European elites, increasing the legitimacy of both grassroots and official initiatives. Public support for the UK to seek a stronger relationship with Europe rather than with the US has grown significantly since Trump returned to office, and the UK–EU Security and Defence Partnership has unlocked progress towards closer post-Brexit defence and security arrangements. Moreover, European support for Ukraine remains high and in 2025, Europe overtook the US as the leading provider of military support to Kyiv. However, when respondents to a YouGov survey in December 2024 were asked about continuing support until Ukraine wins, support decreased, suggesting that the window for creating durable security guarantees may be closing. Yet, these trends also indicate the existence of political capital which Europe can leverage to be bolder in integrating Ukraine into the EASA.

Increased European Spending on Defence

Europe is rearming and has agreed to a new NATO defence spending target of 3.5% on hard military capabilities by 2035, with a further 1.5% allocated to ‘security-related spending’. European priorities include deep precision-strike capabilities (developed by multiple countries) that can directly threaten Russian political and military centres, thereby underpinning European deterrence.

Efforts to Strengthen Nuclear Deterrence

European states are individually and collectively more comfortable with debating the role of nuclear weapons in their defence and deterrence. As mentioned, the policymaker and expert community are actively examining how British and French nuclear capabilities can be better leveraged and how non-nuclear Allies can help strengthen the credibility of nuclear deterrence. The UK–France Northwood Declaration – which launched the UK–France Nuclear Steering Group – sends a clear message of close nuclear coordination. Meanwhile, France has reiterated its willingness to consider how its own nuclear deterrent may play a more prominent role in European security, with non-nuclear allies – namely,  Germany and Poland – also having expressed an interest in better leveraging the French and British nuclear deterrents for their security.

However, persistent challenges remain. British and French nuclear capabilities and posture – in their current configuration – would struggle to independently (in other words, without US backing) offer effective credible extended deterrence to Allies against the full range of threats that Russia may pose to NATO – especially its eastern members. Moreover, France remains outside the formal NATO nuclear deterrence architecture, and the European dimension of the French deterrent remains unclear.

The Weaknesses of CRINK

At the same time, Europe’s adversaries are plagued by weaknesses that are ripe for exploitation. For one, CRINK is not a strategic alliance but a marriage of convenience and opportunity. While the notion is useful for framing US great power competition thinking, it does not necessarily translate strategically for Europe, because it fails to capture the unique drivers and asymmetric relationships within the group. For example, there is little chance of decoupling Russia from China, but there is scope to exploit Russia’s strategic depth – its partners – especially economically. Furthermore, Russia’s poor military performance in Ukraine has eroded the image it attempts to project of the ‘second strongest army in the world’, which should give Europe confidence in its ability to deter and defend against Russia with reduced US support.

Russia’s Power Has Diminished

Most convincingly, Russia’s inability to seize Ukraine has damaged its regional and international standing. In September 2022, while fixed on Ukraine, Russia failed to fulfil its regional leadership role by ignoring renewed and escalating clashes between Kyrgyzstan and Tajikistan, leading Kyrgyzstan to cancel Collective Security Treaty Organisation (CTSO) joint military exercises that month, making the CTSO effectively moribund. 

In 2024, Russia was similarly unable to help former President Bashar-al Assad cling to power in Syria and, in the process, lost a valuable foothold in the Middle East. This, in turn, weakened Russia’s support for its regional partners in Lebanon and Iran, under renewed Israeli military pressure following the 7 October 2023 Hamas attacks. In 2025, Russia was too regionally weakened to provide diplomatic or military support to Iran, and its S-300 air defence systems failed to defend Iran from Israeli and US military strikes. Despite a comprehensive Kremlin interference campaign in Moldova’s 2021 parliamentary elections, and the country’s 2024 EU referendum and presidential elections, and 2025 parliamentary elections, this small European country has withstood Russian pressure and assembled a strong democratic mandate to integrate into the EU, an opportunity which the EU should immediately seize. With Russia structurally weakened – politically, militarily and economically – Europe now has a golden opportunity to build a resilient EASA against it.

Priorities for the Future EASA

The geopolitical realities Europe faces, therefore, suggest a period of sustained external and internal pressures. A new EASA cannot be formed immediately and there will be a transitional period towards any future framework. In the near future, credible conventional and nuclear deterrence must be the overarching priority to provide Europe with the time and space to rearm and build a resilient EASA. This will enable Europe to restore stability and, if possible, deliver strategic advantage against Russia and its partners. The following recommendations for European policymakers suggest how to build such an EASA.

Recommendations for European Policymakers

1. Define a Long-Term Strategy

The notion of ‘architecture’ in the EASA refers to how states can best organise themselves to deliver their security. As a first step, Europe must clearly define its long-term objectives and desired end-state, which would subsequently dictate the optimal organisational structures and memberships. The US National Security Strategy – with its withering assessment of Europe’s future – will hopefully force European leaders to collectively strategise, rather than be consumed by Euro-Atlantic crisis management. These objectives should have several overlapping dimensions.

The first objective concerns the EASA’s focus on Russia. The Cold War strategy of containment – which the legacy EASA enabled – was conceived by then-US Director of Policy Planning George F Kennan in 1947 but took 42 years to prevail over the Soviet Union. Today, US political scientist Andrew Michta argues that the US has not had a viable Russia strategy since the end of the Cold War, instead relying on a number of failed ‘resets’ of the relationship, but failing to define a clear end-state. In Russia, on the other hand, Putin has remained single-minded in seeking ‘imperial reconstitution’. Some European leaders have called for the defeat of Russia but still struggle to define the conditions. At the 2023 NATO Summit, an Alliance-wide Russia strategy was promised, but the commitment was quietly dropped with Trump’s return.1.  For NATO, such a strategy is imperative, and as a military alliance it should heed the master principle of war of ‘selection and maintenance of the aim’ as the best cohesive unifying effort for allies.

The response to the war in Ukraine has also exposed NATO’s impotence. Assistance to Ukraine has been delivered in great part via member bilateral agreements and the EU placing economic pressure on Russia through sanctions. As NATO prepares to fight, the EU should continue to underpin and strengthen the Euro-Atlantic economic architecture, leading the financial and industrial acceleration to deliver both NATO’s new 5% defence expenditure goal, and its Capability Targets, which determine what each Ally must militarily provide to NATO.

The future EASA must for now be built against Russia, but Europeans must also determine how it can be built without Russia. Researchers Ondřej Ditrych and Martin Laryš have imagined four possible models for the future EASA following Russia’s full-scale invasion of Ukraine: unstable balance; positive stable balance; negative stable balance; and concert. They concluded that the current situation of an ‘unstable balance’ model remains the most likely scenario. They further conclude that a ‘positive stable balance’ model would be a possible security upgrade from a European perspective – even without strong norms and behaviour foundations – if Russia is increasingly under pressure militarily on the battlefield in Ukraine and economically at home, with Europeans maintaining their support for Ukraine.

The second long-term objective for the EASA would be to ensure security for and around Ukraine. The fate of Ukraine is the decisive factor between a positive or negative stable balance model. However, 11 years after the annexation of Crimea, and three years after the full-scale invasion of Ukraine, Europe still struggles to articulate the precise goal it wishes to achieve in Ukraine, all while allocating €43.5 billion per year of European bilateral and EU institutional funds to Ukraine since 2022. A strategy must define exactly what Ukrainian victory looks like, and, more importantly, should clearly spell out Russian defeat. Andriy Zagorodnyuk, a former Ukrainian defence minister, has argued that the theory of victory over Russia should be ‘strategic neutralization’, to go beyond deterrence and build a ‘viable, sovereign and secure [Ukrainian] state under constant military pressure’, a precursor to the European vision of the EASA. Such an approach would seek Russian operational paralysis through denial and exhaustion of Russian offensive capability, an outcome that would suit both NATO and Ukraine considering the linkages between the Nordic, Baltic and Ukrainian theatres that can overstretch Russian conventional capabilities. 

In addition, in the event of war between NATO and Russia, Ukraine would fight alongside the Alliance regardless of the question of membership, a scenario which adds a significant deterrent value to NATO. There is a prevailing false assumption within Europe that Euro-Atlantic security can automatically be achieved if Ukraine joins NATO – a distant prospect. NATO must first and foremost be strengthened politically and militarily, so that if the time comes, it is in a position to protect Ukraine.

The third objective should be an EASA that embraces interests as well as values. The preamble to the North Atlantic Treaty reaffirms collective values: NATO is ‘founded on the principles of democracy, individual liberty and the rule of law’. Similarly, the Conference for Security Cooperation in Europe Final Act of 1975 – a key part of the EASA, which laid the foundations for the creation of the OSCE – is based on 10 values-based principles. In Putin’s 25 years in office he has violated all 10 principles – some multiple times – leading to the conclusion that the 1975 Final Act is defunct, and perhaps even the OSCE itself is defunct. With intensifying great power competition, US values diverging from Europe’s, and states such as Hungary exhibiting contrary values, the EASA reflects a realist rebalancing towards interests. These interests must be identified, agreed on and prioritised. Recent polling in the UK suggests that this view is also becoming widespread with the public.

The fourth objective must be that the EASA has a global dimension in the long term. Since 2022, Euro-Atlantic security has de-facto gone global. Poor Russian military performance has forced Russia to rely increasingly on direct and indirect support from China, North Korea, Iran and other aligned states. Although Putin is transfixed with Ukraine, he is also carefully considering Russia’s global position. In March 2023, Russia updated its 2016 Foreign Policy Concept, describing itself as a ‘Eurasian and Euro-Pacific power’. This provides a view of its shifting international mindset, pragmatically emphasising different parts of its foreign policy to European, Indo-Pacific or Middle Eastern partners that are now an indispensable source of support.

Although Europe’s most acute security threat comes directly from Russia, it must increasingly look beyond the Euro-Atlantic to protect its interests and project its influence. Crucially, if China invades Taiwan (and US intelligence assesses that 2027 is China’s likely window of opportunity) it will have significant impacts on Euro-Atlantic security, as it would also provide Russia with an opportunity to test NATO while the US is engaged elsewhere. Ukraine has been very successful at fostering global friendships, especially within the Indo-Pacific – Japan, South Korea, Australia and New Zealand have been providing growing assistance. These connections drive greater security partnerships between the Euro-Atlantic and the Indo-Pacific, including through significant defence–industrial partnerships. The rise of global authoritarian threats means that Euro-Atlantic democracies must stick together: against Russia, in support of Ukraine, along interests and values, and within a global context.

2. Strengthen NATO to Work for Europeans

NATO remains the world’s most successful military alliance, and Russia’s war against Ukraine has rejuvenated its defence and deterrence posture, after 30 years of expeditionary crisis-management operations. However, despite its might and pre-eminence within the EASA, NATO is also extremely vulnerable to fluctuations in US policy. Putin – especially after an ineffectual military performance in Ukraine – knows that he cannot defeat NATO militarily and his best chance of victory is defeating NATO politically. By conducting repeated airspace violations and drone incursions into NATO territory, Russia is already testing NATO’s resolve. The Alliance also faces internal pressures resulting from diverging US interests and behaviours. 

But despite these challenges, NATO remains the best way, by far, for European states to organise their security. NATO’s greatest asset is its integrated command structure.2.  Furthermore, it has regional defence plans that are extrapolated from national defence plans – from the Nuclear Planning Group it has Dual-Capable Aircraft nuclear-sharing agreements – and it benefits from secure communications. European states must ensure that they can optimally operate within NATO even if the US is engaged elsewhere. As a follow up to the US National Security Strategy, US officials have set 2027 as a deadline for Europe to provide the majority of NATO’s conventional defence capabilities and the US could withdraw from some NATO planning processes if progress is not made. Therefore, for Europeans to save NATO and continue to enjoy its protections, it must be strengthened quickly.

First, to do so, European states must not attempt to replicate the US political or military contribution to NATO and must understand that the US has a unique role. Instead, through the NATO Defence Planning Process, Europe should identify its own capability gaps and the gaps that may emerge due to US redeployments to the Indo-Pacific, in order to plan for US withdrawal from Europe. Furthermore, European states should prioritise developing systems with the greatest European deterrence effect on Russia, such as deep precision strike capabilities. NATO’s creation of new activities in 2025, such as ‘Baltic Sentry’ and ‘Eastern Sentry’, as a direct response to Russian incursions, have been European led and resourced, which demonstrates that European states can organise within NATO. Still, these activities fall short of what would be required to prepare for a direct military confrontation with Russia.

Second, Europe must focus on defence and deterrence to strengthen NATO. The 2003 ‘Berlin Plus’ agreement ensured that the EU could access NATO’s command structure, planning and assets for crisis-management operations. However, following operations in Afghanistan and the Sahel, European states have lost the political appetite for such operations. Therefore, Europe should refresh the Berlin Plus agreement, which would enable coalitions of the willing among European NATO members to access NATO structures and capabilities, even if the US were not engaged or there was no European consensus, and to shape a command structure that works for Europeans without the leadership ‘glue’ that the US provides.

Third, Europe must enhance regionalisation within NATO. The concept of regionalisation under five Regional Planning Groups was central to NATO’s first 1950 Strategic Concept. However, modern-day NATO has opted for a ‘360-degree’ approach to security due to political reasons, an approach which was formally adopted at the 2016 Warsaw Summit, and is assured by the politico–military power of the US. Yet, with the US currently pursuing other defence priorities, European states will be concerned about their own deterrence and defence abilities. Therefore, instead of organising for the whole of the Defence and Deterrence of the Euro-Atlantic, European states should ‘own’ the regional plans as an organising principle, making the overall challenge far more manageable. The UK led-Joint Expeditionary Force is already demonstrating this capability to a large degree, but the UK should seek to formalise its role within NATO’s northern regional plan and provide an excellent model to be replicated across Europe. By strengthening NATO and enabling it to work better with reduced US leadership and input, Europe stands the best chance of organising its own security and deterring Russia. 

3. Consolidate Minilateral Security Arrangements

NATO and the EU dominate decision-making within the EASA, but organisational politics and the requirement for unanimity has led to a proliferation of minilateral security arrangements. These ad-hoc formats are currently politically expedient for Europeans to manage Trump in a ‘damage control’ mode and coordinate support for Ukraine, because small group cooperation is beneficial for developing ‘capability coalitions’. However, minilateral arrangements are also politically lazy solutions and offer only a band aid on the challenges facing Europe: they often lack power, capacity and legitimacy, and they tend to compete with one another. Furthermore, these arrangements might be able to fulfil crisis-management functions, but are incapable of fulfilling defence and deterrence functions as they lack the ability to operate, plan or enable deployments independently from NATO. Existing European minilateral security arrangements must be consolidated.

Indeed, experts at the conference held by RUSI in July 2025 were strongly in favour of renewing existing structures, rather than creating new ones. They concluded that the patchwork must be ‘interlocking, not interblocking’, and requires ruthless consolidation based on added value, geopolitical realities post-2022, complementarity to NATO, and an ability to deliver European strategy.

Despite the transformation of the EASA, the UK, France and Germany still dominate European decision-making and have the most scope to shape the next EASA. Bringing the E3 (UK, France and Germany) together with the Weimar Triangle (France, Germany and Poland) would develop the strongest European quad of powers, providing a strong leadership group and bridging NATO and the EU. Germany has traditionally eschewed ad-hoc formats in favour of the political comfort of multilateralism, but it is likely that its growing defence spending and leadership aspirations will change their approach. Furthermore, UK–France cooperation has long been deep, and is now coalescing around operational aspects – especially sending a potential military mission to Ukraine – and nuclear aspects, creating a strong nucleus for other countries to rally around.

Identifying opportunities for cooperation and coordination outside existing structures is particularly important for nuclear deterrence and assurance. Considering France’s willingness to bolster the European dimension of its nuclear deterrent, bilateral and minilateral agreements may provide Paris with a way to do so while remaining outside the Nuclear Planning Group. The July 2025 Northwood Declaration and the accompanying newly-established UK–France Nuclear Steering Group could be one such forum for better integrating French nuclear thinking into European and NATO nuclear planning, and conversely, does not commit Paris to direct coordination on nuclear operations. A similar role could, in principle, be carved out for the Franco-German Defence and Security Council and the Franco-Polish Treaty on Enhanced Cooperation and Friendship. At the same time, unlike in other aspects of the EASA, consolidating these minilateral arrangements may be more politically problematic as they may start to duplicate the work of the Nuclear Planning Group and raise questions over its role, or unhelpfully and incorrectly signal Europe’s intent to supplant the US nuclear deterrent on the continent.

Minilateral security arrangements, therefore, are useful but cannot realistically replicate the political and military heft of NATO, even a NATO with a disengaged US. Therefore, complementarity of these arrangements to NATO must be a fundamental organising principle, and European states must not fear jettisoning arrangements and groups that do not meet this immediate requirement.

4. Modernise Military Confidence-Building Measures

The OCSE should identify where it can continue to add value, to avoid becoming moribund. Existing confidence and security-building measures (CSBMs) agreed in the Vienna document (originally agreed in 1990 and updated in 1992, 1994, 1999 and 2011) concern traditional military capabilities such as artillery, where simply creating a buffer zone out of gun-line range can contribute to a stable ceasefire. However, the speed of technological innovation through the war in Ukraine is unprecedented, which makes older doctrine largely obsolete. Measures to control the use of advanced kinetic systems such as drones and long-range glide bombs are required, as are confidence-building arrangements to support non-kinetic capabilities such as cyber, and AI control and responsible use. One issue that has not disappeared, however, is the need for transparency and predictability. This drove the CSBMs of the Cold War and post-Cold War eras and needs to be applied to the new circumstances of the 2020s and beyond, especially on lines of contact or proximity between Russia and its European neighbours.

European states must be realistic about what could be achieved in the short term and not aim for perfect binding commitments, treaties or other risk reduction efforts. Furthermore, where possible, regional measures should be pursued – for example, in the Arctic, which was a specific region singled out for US–Russia cooperation in the US–Russia draft Ukraine peace plan – in preference to Euro-Atlantic wide if conditions are not met. Although there is a lack of trust in Russia, there remains scope for persuading Putin that engaging and fulfilling Russia’s OSCE-based commitments are in its own interests, as there are areas Moscow should be concerned about: for example, Russia’s new, long and exposed border with Finland – and therefore with NATO. Recent tensions underscore the continuing need for risk reduction and transparency provisions. Indeed, if Russian aircraft in NATO airspace were shot down, these measures would be needed urgently.

5. De-Silo Considerations for Conventional and Nuclear Contributions to European Defence and Deterrence

Euro-Atlantic security debates tend to decouple conventional and nuclear deterrence, escalation management and risk reduction – a separation which is much less pronounced in Russian deterrence thinking. The EASA must therefore adopt an integrated approach to capability and deterrence planning, especially as shifts in US conventional commitments risk having an impact on the credibility of nuclear deterrence in Europe. While forward-thinking should be undertaken on the future of the UK and French nuclear capabilities and posture, the bolstering of European advanced conventional capabilities is the most immediate way of addressing concerns over the credibility and effectiveness of nuclear deterrence in the Euro-Atlantic. This must include, inter alia, investments into IAMD and deep precision strike, which will help introduce flexibility into Europe’s deterrence options and ensure greater resilience against Russian threats – both conventional and nuclear. Investments in conventional capabilities, by non-nuclear allies in particular, can allow for a ‘division of labour’ on deterrence among NATO Allies, allowing European states – including non-nuclear allies – to hold Russian critical assets at risk, short of resorting to nuclear strikes.

At the same time, nuclear and conventional planning and exercises in the Euro-Atlantic space should be integrated more closely, where possible. This integration is, of course, challenged, inter alia, by the fact that France remains outside the Nuclear Planning Group and therefore does not contribute to NATO nuclear planning, making it difficult to include nuclear contingencies in conventional exercises and planning within NATO, and vice versa. As mentioned above – and as is explored in greater detail in the forthcoming RUSI paper on nuclear weapons in EASA – there are possible ways to start bridging these gaps, including through bilateral or minilateral discussions outside NATO frameworks, while maintaining the deterrent benefits of multiple decision-making centres. To this end, the UK–France Nuclear Steering Group may be of particular value as a bridge between French nuclear thinking and nuclear planning inside NATO.

A forthcoming RUSI paper on nuclear weapons in EASA will touch on these options and debates in greater detail.

6. Develop Options for Managing Risk

Europe must also contribute to risk management efforts, especially as more advanced conventional capabilities are introduced into the Euro-Atlantic theatre, which could create new escalatory risk dynamics. Deep precision-strike capabilities and new IAMD systems will be seen by Moscow as destabilising and may create escalatory and entrapment risks. Efforts focused on joint planning and the promotion of joint risk perception across Europe will be paramount. 

The current state of the Russia–US relationship, and uncertainties over whether and how to include China in any arms control efforts, means that the prospect of any formal arms control agreements in the near future is slim. In fact, NATO would be wise to approach Russia’s offers of arms control with a healthy dose of scepticism and to ensure that any arms control efforts do not inadvertently place the Alliance in a disadvantageous position. The focus should be on identifying opportunities for agreement over broad principles, as well as more specific – if limited – opportunities for risk reduction at the margins, an approach which has been proposed by arms control expert and RUSI Senior Associate Fellow Amy Woolf. This may be achieved through a combination of high-level political statements and – eventually – by engagement on discreet and limited areas of mutual concern, including through exchanges between non-governmental experts.

Such an approach will have to be balanced carefully against the necessity to bolster European deterrence capabilities through the development and fielding of advanced conventional systems, described earlier, which Russia will perceive as threatening. Some have argued that, in fact, pursuing such a build-up and associated Russian risk perception can be leveraged to pressure Moscow into arms control. While this may be the case, converting increased risk perception into arms control creates a very high risk of miscalculation and may instead result in an arms race. To avoid this, a certain level of trust and willingness to communicate directly on risk reduction measures by Russia, the US and potentially China is necessary. While the willingness to communicate directly is currently missing, it could be built up over time through the limited approach to risk reduction mentioned earlier. 

Conclusion

The EASA is under the greatest external and internal pressure since its inception. The international rulebook is changing, and European states must be prepared to provide for their own security, to reshape an EASA that is no longer working, and organise around collective interests to avoid falling behind strategically. Europe must focus on building credible deterrence in the short term to buy time and space to deliver an EASA for long-term stability and, if possible, a strategic advantage. 

The UK is ideally placed to lead on the development of a long-term strategy for Euro-Atlantic security. It is one of two European nuclear powers, has a very close bilateral relationship with the US and a ‘NATO first’ defence policy, is a strong supporter of Ukraine, and a leading member of most organisations within the EASA, enabling it to have significant leverage in consolidating European minilateral security arrangements under the NATO umbrella. 

The UK also plays a central part in NATO’s command structure and can therefore influence Europe-specific adaptations to NATO’s command structure, NATO Defence Planning Processes and the Nuclear Planning Group to ensure that the Alliance can function as necessary when the US is distracted or committed elsewhere. On both of these points, the UK can make the greatest contribution by furthering its ambition to ‘lead and galvanise’ security in northern Europe, which is the focus of a further publication for RUSI’s Future Euro-Atlantic Security Architecture project.

Both nuclear and conventional deterrence in Europe can be bolstered through closer integration of these two aspects and closer coordination between the UK and France and their non-nuclear allies to identify the most effective division of labour on deterrence. This aspect of EASA is the focus of a further RUSI paper in this series.