The Impact of Evolving Threat Perceptions on the Transatlantic Alliance

Introduction

This paper examines how shifting threat perceptions are affecting definitions of national security in the US and Europe, and considers the future implications for the transatlantic alliance. By exploring key themes such as great power competition with China and Russia, regional crises in the Middle East and Africa, and transboundary security threats, such as climate change and pandemics, the paper looks beyond day-to-day political developments – including the current administration of President Donald Trump and current key European governments – to focus on broader, longer-term structural changes in how threats are perceived and their interaction with foreign policy interests.

This paper argues that the transatlantic alliance faces growing differences over threats and priorities, but that it can remain a pillar of global stability if both sides embrace a rebalanced partnership, with Europe assuming greater security responsibility and the US remaining engaged. Sustaining this model will require political will, flexible institutions, deeper dialogue, stronger European defence spending and a continued US commitment to the alliance.

Methodology

The analysis for this paper draws on a combination of secondary foreign policy literature, official statements from political leaders, and government strategy policy documents.

This paper was made possible (in part) by a grant from Carnegie Corporation of New York. The statements made and views expressed are solely the responsibility of the author.

The History of the Transatlantic Alliance and the Threat Perception

The foundation of the transatlantic alliance dates back to the Second World War. In 1941, the US and the UK signed the Atlantic Charter. NATO was established in 1949 in the aftermath of Nazi Germany’s defeat, reflecting a sustained US interest in preserving a favourable balance of power in postwar Europe. During the Cold War, Europe became a central theatre of global security, underpinned by shared transatlantic values, such as democracy and a market-based economy.

Naturally, even during times of relative transatlantic harmony, the US and Europe have still looked at the world through different lenses, informed by, among other things, their relative strategic roles and power projection capabilities in the world, their geographical position and their history. However, despite occasional differences, the Alliance largely maintained a common grand strategy throughout the Cold War. However, this transatlantic consensus began to erode after the Cold War, as the Alliance’s purpose grew less certain, and Europe became less central to US strategic thinking amid broader geopolitical and geoeconomic shifts.

This period was marked by increasingly complex patterns of threat perception rather than core strategic alignment. Although the US and European countries often collaborated to address emerging challenges – such as instability in the Western Balkans in the 1990s – and NATO’s role evolved to take on new responsibilities, a growing divergence in national security interests between Washington and its European allies became evident. In the aftermath of the 9/11 attacks, the emphasis by the administration of President George W Bush on pre-emptive military intervention to counterterrorist organisations, on other non-state threats and on rogue regimes led to fragmented European support for US military engagements in Afghanistan and Iraq, and concerns that the US was undermining international law.

At the same time, this period marked the high point in US support for an expansive vision of European security, notably with NATO’s enlargement commitments to Ukraine and Georgia in 2008. President Barack Obama’s subsequent efforts to scale back US military involvement in the Middle East and reorient US strategic focus towards Asia further reinforced the perception that the US was moving away from a Europe-centric security agenda.

The transatlantic divergence in perceiving external threats was further exacerbated by the election in 2016 of President Trump, who in his first term openly challenged conventional foreign policy approaches that had embedded US power in institutions and norms. Trump most notably criticised NATO as an ineffective alliance and even threatened to withdraw from it, while making repeated overtures to Russia. He also identified China as the predominant security and economic threat to the US, helping consolidate a new hawkish foreign policy consensus on China in Washington.

The election of President Joe Biden in 2020 – while instrumental in repairing ties between Washington and European capitals – did not fundamentally reverse the US’ strategic drift away from Europe. The war in Ukraine temporarily returned Europe to the centre of the Biden administration’s foreign policy agenda, alongside countering China in the Indo-Pacific and addressing instability in the Middle East, especially following Hamas’ 7 October 2023 attacks in Israel.

This overall trajectory towards divergence appears to have been confirmed by Trump’s return to the White House in 2025. However, while it is tempting to portray Trump as marking a fundamental departure from previous Republican administrations, he shares key similarities with Ronald Reagan and George W Bush in terms of threat perception, and regarding the role of the US in addressing these threats. All three of these presidents represent a security-driven approach to foreign policy, characterised by a belief in peace through strength and a general scepticism about multilateralism.

A shifting transatlantic threat perception also implies a divergence in how the two sides of the Atlantic define their own interests. For the US, the centrality of the European project has faded in strategic relevance when there are other priorities to consider. Trump even argues that the EU constitutes a direct threat against US economic interests. Meanwhile, some European leaders argue that the US does not share similar values, and is an unpredictable ally and a challenger on trade issues.

Contemporary Transatlantic Threat Perceptions

Russia and Europe

While the US remains essential to Europe’s defence against Russia, both the European theatre and the Russian threat have declined as top US foreign policy priorities. By contrast, defending itself from Russia has become Europe’s dominant security objective since the full-scale invasion of Ukraine in February 2022.

The US stance on Russia has evolved significantly over the past decade. Every US president since George W Bush has sought to stabilise relations with Moscow. Bush aimed to cooperate with Russian President Vladimir Putin on the global war on terrorism. Under Obama, Secretary of State Hillary Clinton pursued a ‘reset’ policy to normalise diplomatic relations following Russia’s 2008 war with Georgia. After taking office in 2016, Trump also sought a rapprochement with Putin, culminating in their summit in Helsinki in July 2018 – although these efforts produced little substantive change. Despite Trump’s personal interest in improving bilateral ties with Russia, most US sanctions against Russia remained in place throughout his first term.

Biden, whose views on Russia were shaped by his long experience with NATO and European security, initially sought to ‘park’ the relationship with Moscow in the hope of preventing further deterioration and allowing the US to shift strategic focus towards China and the Indo-Pacific. This approach was reflected in the Geneva summit between Biden and Putin in mid-2021, where the leaders expressed a desire for more stable relations. Biden emphasised issues such as arms control and cybersecurity, with little mention of Ukraine.

However, Russia’s full-scale invasion of Ukraine – an action preceded by US warnings to European allies and closely tracked by Washington – prompted a major shift in US policy. The Biden administration responded forcefully, framing the war as a direct threat to European security and to the broader rules-based international order. The US rallied its allies to respond by supporting Ukraine militarily.

While the Biden administration frequently grouped Russia and China together as part of what some analysts referred to as an emerging ‘axis of authoritarianism’, also including Iran and North Korea, the second Trump administration has been more sceptical that such an alliance is indeed being constructed. Trump officials ostensibly do not consider the war in Ukraine to be an existential challenge to international security and prefer to associate it with the Biden administration’s foreign policy, as another ‘endless war’ resembling previous US engagements in Iraq and Afghanistan. Trump’s national security team has made it clear that, in contrast to China, Russia does not rank as a top-tier threat to US interests. Considering the US’ constrained resources and Russia’s underperformance on the battlefield in Ukraine, some Trump advisors ask why continuing to invest significant resources in supporting Ukraine is in the US’ interest, leading, among other things, to the US halting some weapons shipments to Ukraine.

In fact, some of Trump’s advisors even see Russia as a potential counterweight to China: a relationship to be leveraged as part of a ‘reverse Kissinger’ strategy. They view Russia as a possible geopolitical asset in addressing questions around energy cooperation, Iran, North Korea and arms control. As a result, Trump has attempted an (albeit inconsistent) diplomatic and economic détente with Moscow, aimed at disrupting the Russia–China axis by making Russia less dependent on China. However, this view is not necessarily shared by the broader US national security community, with many Republican senators still maintaining a sceptical view on Russia and on the fruitfulness of US engagement with Moscow. Trump is at once viewing Russia as a secondary challenge and seeking to normalise relations. He is eager to end the war in Ukraine, but has vacillated between accommodating Putin’s aggression and pushing back against his intransigence, including through threatening secondary tariffs on Russian oil exports.

On the other side of the Atlantic, European views of Russia have also evolved significantly during the past decade, becoming increasingly negative. Except for a handful of countries in northeastern Europe, few European governments regarded Russia as a serious security threat prior to its illegal annexation of Crimea in February 2014. Moreover, this event, – which was at the time considered to be the greatest challenge to the European security order since the end of the Cold War – did not initially provoke a unified response. Major European powers, such as Germany and France, continued to engage with Moscow diplomatically and economically, hoping to prevent relations from becoming overtly adversarial. In fact, most western and southern European capitals did not view Russia as a strategic adversary or even a primary security concern.

It was not until Russia’s full-scale invasion of Ukraine in 2023 that a more coherent European threat perception of Russia began to emerge. Since then, there has been growing consensus across Europe that Russia poses a significant threat to European security and that supporting Ukraine, both militarily and financially, is essential to safeguarding the continent. As a result, the prevailing view in Europe is that its security must now be reoriented towards deterring Russian aggression, requiring substantial increases in defence spending and military readiness.

Even so, notable differences remain in threat perceptions. Countries on NATO’s eastern flank tend to view Russia as an existential threat to their national security, while many western and southern European governments still regard Russia as a distant, albeit serious, concern. For example, Italy and Spain are far more focused on instability in the wider Mediterranean and have been slower to increase their own defence expenditures to defend against Russian threats and satisfy Trump’s pressure campaign.

China and Security in the Indo-Pacific

Competition with China in the Indo-Pacific has become a top US foreign policy priority, regardless of which administration is in power. Although Europe is also toughening its strategic stance toward China, transatlantic convergence on the issue remains constrained.

Over the past decade, the US threat perception of China has become markedly more adversarial. Obama pursued the so-called ‘Pivot to Asia’ – aimed at prioritising the growing challenges posed by China in the region – and the first Trump administration broke with prior convention by identifying strategic competition with China as the US’ top national security concern. This openly adversarial shift was formalised in the 2017 National Security Strategy, which for the first time framed China as a multifaceted threat across military, political, economic and technological domains. The Trump administration also introduced the ‘Free and Open Indo-Pacific’ strategy, which emphasised stronger ties with regional allies – such as Japan, South Korea, Australia and India – to counterbalance China, with a particular focus on bolstering Taiwan’s sovereignty.

The Biden administration largely built upon this approach, reflecting a growing bipartisan consensus in Washington. Biden’s 2022 National Security Strategy announced that the coming decade of competition with China would be decisive. Under his leadership, the US developed a more coherent and integrated national strategy towards China, centred on three pillars: investing domestically, aligning with allies and partners, and competing with China across key sectors. The second Trump administration continues to view China as the US’ foremost national security threat and its only near rival. However, there are divergent views within the administration itself, and it has yet to fully articulate a strategic approach.

Compared to the US, Europe has been slower to recognise the strategic challenges posed by China. It traditionally viewed China primarily as an economic partner, albeit a challenging one. In a strategy paper published in 2019, the EU identified China for the first time simultaneously as a strategic rival, a competitor and a partner. Since then, the EU has developed a range of economic security instruments to address trade and economic challenges related to China, and adopted a tougher foreign policy stance on security issues in the Indo-Pacific, notably on Taiwan.

European perceptions of China as a threat have significantly been shaped by Beijing’s ambiguous behaviour during the Covid-19 pandemic, as well as its material support for Russia’s war in Ukraine. Nevertheless, a coherent, unified European position on China remains elusive, as individual member states continue to prioritise their own bilateral economic relationships with China. Furthermore, while Europe’s view of China has hardened and it has increased its focus on Indo-Pacific security challenges such as Taiwan, these concerns have been overshadowed by the urgent need to address security issues closer to home following the invasion of Ukraine.

China features increasingly prominently in transatlantic discussions, including in bilateral US interactions with European governments and with the EU, and at NATO, where the 2024 summit communiqué singled out China as posing a systemic challenge to the Alliance’s ‘interests, security and values’. However, efforts to align US and European approaches to China have also been hampered by European hesitation about becoming parties to an increasingly hostile US–China competitive environment. Meanwhile, some members of the Biden and Trump administrations have been sceptical that Europe can even play a useful military role in the Indo-Pacific, and instead advise that Europeans concentrate on regional security in Europe.

Economic and Technological Security

Whereas the US increasingly treats economic and technological competition with China as a national security issue, Europe remains more focused on balancing relations with China while building out its own sovereignty.

China has experienced a rapid economic rise since it joined the WTO in 2001, but there are growing widespread perceptions that China does not play by established economic rules. These facts have prompted a significant shift in US thinking about the international economic system. Whereas the Obama administration sought to manage China’s growing influence by negotiating mega-regional trade agreements with partners in Europe and Asia to set new global standards, both Democrats and Republicans have become increasingly protectionist and sceptical of free trade since Trump’s election in 2016.

At the core of this shift is the view that China has systematically undermined the US economy by offshoring American jobs, heavily subsidising strategic sectors, and engaging in illicit activities such as cybertheft and corporate espionage targeting US companies and research institutions. As a result, US policymakers have grown disillusioned with the global economic system and increasingly prefer unilateral actions over multilateral reforms to change the status quo. Some members of the Trump administration even argue that the explicit goal of the US should be to undermine China’s economic and technological rise, so as to undercut China’s ability to rival the US militarily.

While protectionism has now become the norm across both political parties in the US, different administrations have taken their own unilateral approaches. The Biden administration focused on large-scale incentives – including the Inflation Reduction Act and the bipartisan CHIPS and Science Act – aimed at reshoring manufacturing from China, particularly of semiconductors and for green technologies. In contrast, Trump favoured using tariffs to compel companies to decouple from China. Nonetheless, both administrations agreed on the need to restrict certain critical technologies, such as AI, semiconductors and quantum computing technology, from China and other foreign entities of concern like Russia, Iran and North Korea,, and to strengthen the domestic industrial base to compete more effectively. The US is more willing than Europe to explicitly identify China as an economic threat and implement policies that specifically target China.

By comparison, Europe is generally more dependent on international trade than the US, and the existence of a rules-based order and multilateralism remains a central pillar for the EU. In the economic sphere, this has traditionally translated into Europe’s participation in a rules-based global economic system centred on the WTO. However, the EU has moderated its approach in response to rising economic challenges – from not only China but also the US – by taking steps to better protect its industries from unfair trading practices or large state subsidies. These measures include strengthened foreign direct investment screening and export controls, stricter procurement rules and efforts to counter economic coercion, as well as initial attempts to build a stronger European industrial policy.

The EU is actively pursuing a strategy of derisking – a theme also embraced by the Biden administration but not necessarily the Trump administration, which has toyed with the notion of complete economic decoupling from China. However, the EU remains careful not to single out any particular country or take steps that could be seen as undermining its commitment to the rules-based economic order. Moreover, Trump’s aggressive trade and tariff policies towards the EU and the repeated criticisms of the EU by his administration have generated some unease among Europeans about aligning too closely with Washington where China is concerned. Some voices in Europe have even called for alignment with China against the US on trade.

If the US continues down the protectionist path and seeks to weaponise dependence on US technology – even against its allies, for political or economic gains – Europe will increasingly perceive China and the US as an economic challenge and seek to become less dependent on both.

Transboundary Threats: Climate Change and Pandemics

Both the US and Europe are refocusing on hard security threats, either by diverting resources from transboundary challenges or by addressing them through a securitised lens. Yet Europe still treats climate change as a key security priority, while the US has largely abandoned that stance.

Biden’s National Security Strategy identified climate change and other transboundary challenges as top national security threats. In contrast, the second Trump administration has decisively deprioritised these issues, eliminating entire departments and agencies and significantly cutting funding for programmes addressing such challenges. It is expected that Trump’s forthcoming national security strategy will prioritise managing geopolitical threats from nation-state adversaries such as China, as well as regional threats in the Western hemisphere. A future potential Democratic administration would probably maintain the view of China as the principal existential challenge, thereby conditioning US appetite for multilateral reengagement on transboundary threats.

While Trump has returned to a strong focus on preventing migration, his approach differs sharply from those of Obama and Biden. Rather than addressing the root causes of migration – which was a priority for both Obama and Biden – Trump has pursued a security-driven migration policy focused on the domestic border. His administration has even threatened to deploy US forces on Mexican soil to stem migration and combat the illicit drug trade, and has carried out strikes against alleged Venezuelan drug boats.

In Europe, transboundary security threats such as climate change and pandemics have long been recognised by governments as posing significant security challenges. The EU remains particularly concerned about their potential to generate spillover effects, such as refugee flows or an increase in natural disasters, which could have an impact on European stability. However, since the outbreak of the war in Ukraine, European priorities have clearly shifted back towards more traditional security threats, such as territorial defence against Russia. Numerous European countries have cut development aid or redirected funding towards supporting Ukraine. They have adopted a more ‘pragmatic’ approach to addressing climate change amid these urgent security concerns and the need to regain economic competitiveness.

Over the past decade since the so-called ‘migration crisis’ of 2014–15, European governments have also become increasingly hardline about curbing migration flows into Europe through enhanced border security measures, and by offering support to regimes in third countries willing to house refugees, while looking the other way in terms of human rights abuses or humanitarian principles. Relations between the US and Europe have been challenged by Trump over the question of migration. He has been openly critical of the approach followed by many European governments, and leading members of his administration have made public expressions of support for far-right parties in Europe, in part because of their hardline stance on Europe’s migration challenge.

The Middle East

The US’ role and engagement in the Middle East remain critical, despite repeated efforts by multiple administrations to reduce the US footprint in the region. Europe plays only a minor role in shaping Middle Eastern security affairs.

During his first term, Trump oversaw the historic initiative to normalise relations between Israel and several Arab states through the ‘Abraham Accords’. It has also been a key theme of his second term to consolidate this approach, notably through engagement with Gulf states. At the same time, Trump has launched a maximum pressure campaign against Iran over its nuclear programme, and in June 2025 even approved direct US military strikes on Iran’s nuclear facilities.

While major European powers share the US’ concern about Iran’s nuclear ambitions, the US attacks on Iran illustrate diverging transatlantic threat perceptions about the immediacy of the problem and how to best address it: whether through military force or multilateral diplomacy. The decision of the E3 (Britain, France and Germany) to activate the ‘snapback’ provisions of the Joint Comprehensive Plan of Action (JCPOA) has brought the Europeans closer to the US position: that Iran must be coerced into giving up its nuclear ambitions. Still, there are differences underpinned by the extensive US military presence in the Middle East and its close security partnerships with regional states. Even as the US attempts to redirect its focus to China in the Indo-Pacific, any military drawdown from the Middle East could be offset by the fact that the region continues to serve crucial geopolitical and economic interests for the US. In fact, there are recent examples of the US prioritising engagement in the Middle East above commitment to Europe, including in terms of supply of weapons.

Understanding different approaches within the transatlantic alliance to the Middle East is crucial to understanding the pressures on US military resources and commitments abroad. For Europe, the region is generally considered part of its wider neighbourhood, not a priority in terms of defence and security – this view has become further embedded by the more immediate security challenges in Eastern Europe. Despite the Middle East’s geographical proximity and the impact of its regional developments on Europe, European countries have struggled to develop a common approach to the Middle East, with the crisis over Gaza exposing far-reaching divisions within the continent. As a result, the Middle East remains central to European concerns regarding immigration and terrorism, but Europe’s ability to exert influence in the region is significantly limited compared with that of the US.

The Obama, Biden and Trump administrations all pledged to withdraw from ‘endless wars’ in the Middle East following the Bush administration’s war on terror, but despite their repeated efforts to reduce US regional involvement, the Middle East continues to command outsized strategic attention in Washington. Biden’s controversial decision to withdraw from Afghanistan was motivated by the need to prioritise more pressing security challenges in East Asia. However, despite his attempt to shift focus, he again became deeply involved diplomatically in the Middle East to address the Israel–Gaza conflict following the 7 October 2023 attacks by Hamas on Israel.

Trump has continued the strong focus on resolving the Gaza crisis. The US-orchestrated peace deal between Israel and Hamas in October 2025 was widely praised by European leaders.

Africa and Latin America

The US is scaling back its engagement in Africa in favour of renewed involvement in Latin America to curb illicit drug trafficking and migration. Europe, by contrast, feels the direct impact of insecurity spilling over from Africa and is more willing to focus its efforts there.

While Biden made a concerted effort to engage with Africa, including hosting the first US–Africa Leaders’ Summit in Washington in 2022, US engagement has generally been limited. Africa’s strategic importance is increasingly viewed by Washington through the lens of competition with China over access to critical minerals and other resources. Trump has made it clear that Africa is not a priority, cutting security assistance and development funding. US forces, which have until recently actively operated in West Africa to combat terrorism, now face uncertainty due to the potential closure of US Africa Command.

By comparison, Africa continues to be a priority for many European governments, notably over concerns regarding terrorism and large-scale migration. In response to these concerns, there have been various efforts, including through the EU, to bolster economic and diplomatic commitments to sub-Saharan Africa. However, these efforts are often constrained by limited resources, the need to prioritise challenges closer to home, and the lack of an effective European approach to key security issues in Africa. The collapse of France’s security engagement in Francophone West Africa between 2022 and 2025 has left Europe with little ability to affect Africa’s security, and left Europe reliant on the US for regional counterterrorism efforts, further exacerbating transatlantic tensions over Europe’s approach to its security.

In Latin America, Obama and Biden administrations primarily focused on addressing root causes of migration to stem immigration into the US, but otherwise maintained a relatively low profile in regional affairs. By contrast, the second Trump administration has taken a more active role in the Western Hemisphere under Secretary of State Marco Rubio, emphasising migration control, fighting drug trafficking and competing with China – going so far as to threaten territorial expansion of the Panama Canal to deny China’s access. For Europe, Latin America is not viewed as a major security threat, although concerns over illicit narcotics trade persist, and the EU has sought to bolster economic relations with the region.

Convergence and Divergence in Transatlantic Alliance Threat Perceptions

As outlined in the areas of engagement above, threat perceptions are dynamic and far from monolithic across the transatlantic alliance. Despite significant differences between US and European threat perceptions – some of which have been amplified by Trump’s return to the presidency – there remain substantial areas of convergence. Today, both Washington and major European capitals view great power competition, characterised by rising multipolarity and a decline in Western influence, as a central feature shaping international relations.

Although European governments would prefer to keep the US engaged in Europe and that the (probably inevitable) drawdown of US military presence from the region is coordinated and phased, European policymakers have a broad understanding that the US must prioritise the question of China’s rise in the Indo-Pacific. As a result, European governments increasingly recognise that they can no longer rely solely on the US as their primary security provider and that they must assume greater responsibility for their own regional defence.

In view of this adjustment, European countries are seeking to step up defence spending, and the Trump administration is pressuring NATO to shift towards greater European leadership, moving away from the historically US-centric model. At the June 2025 summit held in The Hague, NATO allies committed to reaching 5% of GDP on defence spending by 2035. Trump clarified that he will remain supportive of NATO, albeit with a less strong US leadership role. Both sides of the Atlantic thus agree now on the need for Europe to become more self-sufficient in managing its security challenges, with limited or no US involvement, while the US refocuses its strategic priorities elsewhere.

However, despite this broad transatlantic alignment on global geopolitical trends, significant divergences remain regarding how specific threats are perceived. Unlike during the Biden administration – when the US and Europe largely shared a common view of Russia as a critical threat to European security and the international order – Trump’s return to the White House has intensified a sharp transatlantic divide on this issue. Europe overwhelmingly views Russia as an existential threat to the European security architecture, while Trump has deprioritised Russia as the foremost threat and pursued bilateral engagement aimed at diplomatic and economic normalisation, as well as cooperation on select geopolitical issues. His administration expects Europeans to step up to defend against the Russian threat.

This approach has raised deep concerns among European governments – particularly those in Central and Eastern Europe – about the risk of a US–Russian grand bargain made at the expense of Ukraine and smaller European states. This schism extends to the conflict in Ukraine, which is still seen in most parts of Europe as an existential struggle to defend the European security order from a revanchist and imperialist Russia. By contrast, the Trump administration sees Ukraine as a localised issue, not as a threat against NATO per se or a conflict with far-reaching ramifications for international security. More broadly, there appears to be a growing division between the Euro-Atlantic project – which now appears geographically limited to the current borders of NATO – and the European project, which continues to advocate for EU enlargement to countries such as Ukraine.

With respect to adversarial states, such as Iran and North Korea, the US and Europe share a common goal of preventing nuclear proliferation and maintaining regional stability, although their approaches often diverge. During the Obama administration, close cooperation took place within the E3+1 framework (the E3 & the US) to advance the JCPOA, which sought to limit Iran’s nuclear programme in exchange for sanctions relief. However, the first Trump administration unilaterally withdrew from this agreement, upending this cooperation. Diplomatic efforts concerning Iran’s nuclear programme have continued both under Biden and into Trump’s second term, but Trump’s support for strikes on Iran’s nuclear sites has generated tensions with European governments, which do not necessarily share the same threat perception about the acuteness of the Iranian nuclear threat, nor the belief that this threat can be solved through military means.

The US has an extensive military presence in the Indo-Pacific, and treaty-bound relationships with neighbouring Japan and South Korea, in contrast to Europe’s much more limited regional role. Consequently, the instability on the Korean peninsula is viewed as a far greater direct threat to US security interests than to Europe’s, where it is primarily viewed as a regional issue within Asia but with relevance for international order and arms control. Moreover, the Trump administration’s investments in modernising the US nuclear arsenal and its assessment of a potential new ‘Golden Dome’ missile defence programme to address nuclear threats, such as those from North Korea, have heightened transatlantic concerns about the onset of a renewed nuclear arms race that could leave Europe vulnerable.

The US and Europe occasionally align in their strategic outlooks on issues related to Africa and the Middle East, but they also have major differences. For example, the US and France have collaborated closely on counterterrorism efforts in West Africa for many years; however, these operations are winding down as both sides are compelled to reduce their presence in the region. In the Middle East, cooperation has varied depending on the political leadership: the Biden administration consulted regularly with European partners in response to the Israel–Gaza conflict, whereas the Trump administration has often pursued a more unilateral approach – although its Gaza peace plan has received endorsements from European governments.

The US and Europe similarly appear to be diverging in the realm of transboundary threats. While the US is deprioritising such challenges in favour of great power geopolitical competition, Europe continues to invest in addressing climate change and global health threats, particularly in the relative absence of US engagement – although it faces resource constraints. Even so, both the US and Europe are prioritising preventing illegal migration using an increasingly securitised approach.

An additional significant area of divergence between the US and Europe concerns the multilateral system itself, and the role of multilateralism in defending against external threats. While US support for multilateral institutions has fluctuated over recent decades, Europe regards a rules-based international order as fundamental to its identity and global role. The first Trump administration withdrew from several key international agreements, including the Paris Climate Accord, whereas the Biden administration reengaged with these frameworks, albeit also viewing multilateralism through the lens of strategic competition with China. The second Trump administration has intensified the US critique of multilateralism, withdrawing from the WHO and threatening funding cuts to various UN bodies.

Finally, Trump’s public challenges to established international norms – such as territorial sovereignty, exemplified by his remarks on Panama, Canada, and Greenland – have raised significant concerns among European governments that the US itself could become a disruptive force against the very rules-based international order cherished by Europe. However, the European insistence on a rules-based international order could be in decline, not least since Europe appears so weak and irrelevant on the global stage, and as the continent moves to military rearmament.

Scenarios for the Future of the Transatlantic Alliance

The future of the transatlantic alliance will be significantly influenced by both converging and diverging threat perceptions between the US and Europe. How each side interprets evolving security challenges – and how these views shape their respective roles – will determine the Alliance’s trajectory. Based on this analysis of the evolution of threat perceptions in the US and Europe, four potential scenarios for the Alliance’s future emerge.

Scenario 1: Amicable Transatlantic Split

In this scenario, diverging threat perceptions and strategic priorities lead the US and Europe to pursue separate paths. Europe focuses primarily on its own security concerns, including defending against a belligerent Russia on its eastern flank and managing instability in its southern neighbourhood by itself. Meanwhile, the US refocuses on countering China’s military rise in the Indo-Pacific and on security issues in the Western hemisphere, without European involvement. This results in a gradual US military disengagement and ultimately in withdrawal from Europe, as well as in a diminished role for NATO as the central military organisation in Europe. Consequently, a more autonomous European defence capability is likely to emerge, encouraged by Washington. Despite this strategic separation, relations between the US and Europe remain otherwise friendly, with continued coordination on various foreign policy issues when interests converge, and based on broadly similar values and global outlooks. Areas of tension will remain over regional security, notably in the Middle East.

While certainly plausible, this scenario seems unlikely to materialise in the foreseeable future, considering that the US remains part of NATO, and Europe continues to struggle with developing a coherent common defence posture.

Scenario 2: Breakdown in the European Consensus

Instead of fostering a stronger European defence pillar to complement NATO and enable US strategic refocusing, Europe will further divide over competing visions for its future, as US forces withdraw and the Trump administration divides countries over trade. Rather than coalesce around an integrated European defence policy and transatlantic burden-sharing based on broadly shared threat perceptions, the European consensus fractures. Countries on the eastern flank, which are heavily reliant on US security guarantees, align closely with Washington, while western European powers such as France pursue an independent European defence and foreign policy, distancing themselves from the US and NATO. This division in turn weakens European cohesion and complicates transatlantic cooperation.

This trend could also manifest itself in the US shifting to more of a hub-and-spoke model built around particular allies in Europe, especially in northern and eastern Europe (such as Poland and the Nordic–Baltic Eight – Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, Norway and Sweden). These allies are seen by Washington as loyal, responsible and paying their fair share of the defence burden. Another possibility is that the US rapidly disengages from the European continent altogether, but instead of Europe forming a common defence policy in response, it further bolsters existing initiatives such as the ‘coalitions of the willing’ supporting Ukraine against Russia, resulting in a more fragmented Europe.

This scenario is a likely one, since there is already evidence of states on Europe’s northeastern flank aligning closely with the US and working more closely together in subregional formats.

Scenario 3: Europe Emerges as a Challenger to the US

Diverging threat perceptions increasingly push Europe to see the US as a source of instability and a threat to European interests. European leaders worry that US actions may erode international norms – for example, by violating Greenland’s territorial sovereignty. They also fear that Washington is seeking to undermine European integration and limit Europe’s economic autonomy. In addition, they view US efforts to pursue rapprochement with Russia as contradicting Europe’s security priorities.

In turn, as it loses faith in the durability of a transatlantic alliance based on shared values and common interests, Europe decisively abandons hopes of continued US–Europe cooperation and instead reorients its foreign policy to counter the new US status quo. This shift drives Europe to develop a stronger and more autonomous common foreign and security policy, framed around balancing US power. European leaders also work to forge new strategic partnerships with like-minded middle states worldwide. These partners share similar apprehensions about great power deal-making and US, Chinese and Russian efforts to create separate spheres of influence.

This scenario is unlikely to occur in the foreseeable future, as Europe will continue to engage the US to address common threats such as Russia and China and will continue to struggle to formulate a common security policy.

Scenario 4: A Reinvented Transatlantic Alliance

In this scenario, a stronger European security and defence pillar emerges within the broader transatlantic framework. The US remains committed to European security and to being part of NATO but assumes a less dominant leadership role in the Alliance and maintains a reduced military presence on the continent. Europe, in turn, takes on greater responsibility within NATO and assumes a more autonomous role in managing its own regional security. Meanwhile, both sides continue to collaborate closely on burden-sharing in other global theatres and on critical issues such as counterterrorism, ensuring the Alliance remains effective and adaptable to evolving global challenges. A degree of transatlantic convergence of threat perceptions is conceivable, whereby Europe perceives China as more of a threat than it does currently, while the US remains ready to confront Russia. This results in a shared view of the indivisibility of the threat between the European and Indo-Pacific theatres that can allow for a common threat perception but regional burden-sharing.

This scenario is possible if Europe can manage to coordinate on defence matters in such a way that it keeps the US constructively engaged on European security questions.

Each of these four scenarios offers plausible insights into how the transatlantic alliance might evolve – although none is likely to capture the future comprehensively. Among the four scenarios, the fourth one provides a potential pathway to reconciling divergent threat perceptions through a pragmatic burden-sharing approach. While a comprehensive ‘grand bargain’ between the US and Europe is likely to remain out of reach, this model offers a framework for managing differences constructively. It acknowledges that both sides will continue to pursue independent strategies shaped by their respective threat assessments.

Yet, by fostering a more balanced partnership – with Europe assuming greater responsibility and leadership within NATO, but without triggering a divisive debate about European strategic autonomy that could cause the US to push back or disengage – the Alliance could endure as a vital, albeit transformed, pillar of transatlantic security. This shift will not be without challenges, but this scenario offers a realistic and hopeful vision for adapting NATO to a changing geopolitical landscape.

Conclusion: A Forward-Facing Transatlantic Alliance for the 21st Century

The transatlantic alliance stands at a crossroad, shaped increasingly by diverging threat perceptions between the US and Europe. While both sides broadly recognise the challenges posed by great power competition, multipolarity and global instability, their assessments of specific threats – from Russia and China to climate change – and their definitions of national interests often differ significantly. These differences have only grown more pronounced with Trump’s return to the White House, but they are likely to persist even if a Democratic administration takes power in 2029. Although such an administration might try to manage the divergence differently and reengage with Europe, the rift will still raise serious questions about the Alliance’s durability and future.

Yet despite these tensions, the transatlantic relationship is not fated to fracture. The four scenarios outlined – ranging from strategic divergence to Alliance reinvention – illustrate the spectrum of possibilities ahead. Among them, the most realistic and hopeful path lies in a rebalanced transatlantic partnership, one where Europe assumes greater responsibility for its own security while the US remains engaged, albeit in a less dominant role. This evolving dynamic could allow both sides to manage their differences through coordinated burden-sharing and mutual respect for differing priorities.

Ultimately, the future of the Alliance will depend not on complete alignment, but on the political will and institutional flexibility to adapt to a world where security threats are increasingly complex and interconnected. By embracing a more balanced and transactional partnership that is less steeped in Cold War-era notions of harmonious transatlantic relations, the US–European alliance can remain a cornerstone of global stability, even in an age of strategic uncertainty.

In fact, the ability to remake the transatlantic alliance to be able to respond to the changing international environment is a necessity for global stability in the 21st century. This will require investing in more active transatlantic dialogue and sharing intelligence on threats to develop a more common operating picture. It will also require a greater readiness among European governments to take direct responsibility for their security and to spend the necessary resources on defence. Finally, it will require the US to reconfirm its commitment to the transatlantic alliance as a key component to its approach to an increasingly volatile and dangerous world.