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The European Pillar of NATO in the Era of US Disengagement

The Trump administration’s gradual disengagement from Europe and its adoption of an increasingly hostile rhetoric towards European NATO allies are profoundly reshaping transatlantic relations. Less than a year and a half into Trump’s second presidency, the instances confirming this trend are incredibly numerous and worrying, unfolding at an unprecedented pace and with sheer unpredictability.

A shifting transatlantic balance

Already at the 2025 Munich Security Conference, Vice President J.D. Vance clearly indicated that Washington’s primary perceived threat was not so much Russia or China, but rather an internal values-based fracture within the West.[1] This ideological dimension has progressively overlapped with strategic assessments and appears increasingly to be asserting itself over the latter. At the same time, US priorities are shifting ever more towards the Western Hemisphere and the Indo Pacific, as stressed by the 2025 National Security Strategy,[2] and towards power projection capabilities tailored to that specific theatre, therefore not necessarily relevant to the European one. In addition, the diplomatic crisis among NATO allies over Greenland in early 2026 has put the Alliance’s very cohesion at risk. Meanwhile, the US administration has shown itself willing to undertake military interventions in Venezuela and Iran, without properly consulting European allies, and in the Iranian case carry highly negative and uncertain consequences.[3] To add, following Iran’s closure of the Strait of Hormuz in retaliation for the US and Israel military campaign, Trump threatened to withdraw the US from NATO out of discontent with the European allies’ refusal to send military vessels to reopen the strait by force.[4] All these elements place strain on transatlantic relations, political cohesion, mutual trust, and thus on the very foundations of the Atlantic Alliance.

This does not foreshadow a sudden US withdrawal from NATO – an unlikely scenario in the short term, not least given Washington’s own interests, and the place Europe still holds in its grand strategy, even if diminished – but it does make a scenario of gradual and partial disengagement a reality, as confirmed by the withdrawal of 5,000 American troops from Germany announced by Trump at the beginning of May.[5] In this context, the issue of the European pillar of NATO becomes pivotal.

The European pillar as a pragmatic response

First and foremost, a simple but relevant point must be clarified: the European pillar of NATO does not configure as a European army nor does it have as its future objective the establishment of such a force. The idea of a European army implies full political-military integration, a unified chain of command and shared sovereignty in defence matters, a set of conditions which, under the current EU treaties, is not realistically achievable except in the very long term and at enormous political cost.

The European pillar, by contrast, represents a pragmatic and incremental approach. It does not aim to replace NATO, but to strengthen its European component. It does not presuppose full strategic autonomy, but rather a greater European capacity to act, sustain military effort, and, if necessary, initially withstand the impact of a Russian attack on the Eastern flank. It is a realistic response to a dual constraint. On the one hand, European countries can no longer continue with a business-as-usual approach to transatlantic relations, NATO and the defence of Europe, also in light of the developments mentioned above; on the other, full autonomy cannot be pursued, as it is not currently achievable in practical military and technological terms.

It should also be noted that the European pillar already exists to some extent, insofar as 23 states are members of both the EU and NATO. Therefore, the issue is not to establish it from scratch, but to frame it clearly from a conceptual standpoint, strengthen it and make it coherent and strategically oriented.

From burden-sharing to responsibility-sharing

A tangible indicator of the already ongoing strengthening process of European responsibilities is the recent redistribution of commands within the Alliance’s military structure. For the first time, operational-level commands will shift from US to European leadership. Italy will assume the command of the Joint Force Command (JFC) Naples, while the United Kingdom will lead the JFC Norfolk, and Poland and Germany will alternate at the head of the JFC Brunssum.[6] This is not merely an organisational adjustment: it represents the concrete expression of a shift in military responsibilities within NATO. The United States retains leadership of the three theatre components command – taking up responsibility for Allied Maritime Command in Northwood from the United Kingdom, and maintaining leadership of Allied Land Command in Izmir and Allied Air Command in Ramstein – and of the overall command chain, but direct leadership of key operational commands will be entrusted to European allies. This process is taking place in a context of a gradual relative reduction of the US presence in Europe and increasing European operational capacity. Interestingly, the Supreme Allied Commander Europe (SACEUR) remains however under US leadership.

This overall development is not just a political signal, but also carries strategic and practical implications: it gives European forces a greater voice in NATO planning and execution, and creates a base of experience and credibility that can foster further integrated strategic capabilities at the European level.

A more urgent political debate

At the political and strategic level, the need to strengthen the European pillar is becoming more and more evident. The Greenland crisis represented a turning point, particularly for the Nordic, Baltic and Eastern European states, historically more cautious about strengthening the European dimension of defence out of fear of weakening ties with Washington and thereby undermining US security guarantees against the immediate Russian threat. After the Greenland crisis, precisely because they have always relied predominantly on the US vis-à-vis the Russian threat, these same countries are those feeling most urgently the need to uphold the guarantees of Article 5 even in the absence of any actual American contribution, or in the event of a significant downsizing. At the same time, they remain the most willing to accommodate Trump’s demands, despite the difficulty in deciphering the US president’s conflicting requests.[7]

The perception that US security guarantees under the Trump administration are no longer as solid as in the past – also in light of a softer stance towards Moscow and attempts to normalise US-Russia relations – altered the intra-European debate.[8] Adding to this is Trump’s adoption of positions which are highly controversial and deeply unpopular in Europe, on sensitive issues such as the allies’ commitment to the NATO mission in Afghanistan.[9] Shared sacrifice, in terms of casualties in the conflict, has always been a unifying factor between the United States and its allies, despite the discontent caused by the unilateral withdrawal of American forces from the country completed during the Biden administration. Furthermore, from a European perspective, that sacrifice demonstrated the alliance’s readiness to intervene in support of one of its members under Article 5 commitment, activated following the 9/11 terrorist attacks in 2001.

It must be underlined that the US call for Europe to assume greater responsibility for its own defence, reducing dependence on American armed forces, is not new to the Trump presidency. Previous administrations, starting in particular with that of Barack Obama, which made the “Pivot to Asia” a conceptual cornerstone of its foreign policy, had already signalled to European countries that a greater contribution to defence was demanded from them.[10] The innovative element of the Trump administration’s posture towards European NATO members, beyond its bargaining rhetoric, is the decoupling of US security from that of Europe, dismantling a foundational aspect of the Euro-Atlantic relationship as it had been understood since World War II.

The key issue, however, remains the perception of the transatlantic relationship. Europeans are not yet fully aligned on the assessment of the structural US disengagement from Europe, including its features, timing and implications, nor on the extent and forms to which they should prepare to assume direct responsibilities. However, for the European pillar to be credible, political cohesion is essential.

The role of formats such as the E5 – Germany, France, the United Kingdom, Poland and Italy – may turn out to be fundamental in building critical mass at this stage, given the political, economic and military weight of the countries involved. It represents an example of minilateralism outside of pre-existing institutions, where different sensitivities and interests can lead to vetoing dynamics that significantly reduce their effectiveness.

However, difficulties in Franco-German relations, illustrated for instance by the complexities surrounding the Future Combat Aircraft System (FCAS) programme, demonstrate how challenging it is to maintain cohesion even within such a limited core group.[11] Similarly, fragmentation within the “coalition of the willing” regarding a possible European-led peacekeeping mission in Ukraine highlights the persistent political challenges to achieving an adequate level of unity.[12] Last but not least, the European politico-strategic response to the blockade of the Hormuz Straits seems to get traction within a smaller format involving France, Germany and the UK.[13] The proliferation of ad-hoc groupings, including different European countries, and possibly like-minded countries from NATO or the Indo-Pacific, signals Europe’s efforts to adjust to US disengagement from consultation within the Alliance through other mini-lateral formats. Such an adjustment may favour the build-up of a European pillar of NATO, but there is no automatism in this regard.

Capabilities, industry and credibility

Against this backdrop, the EU has also changed and developed its approach to defence, with a focus on capabilities and defence industrial policy. European Commissioner for Defence and Space Andrius Kubilius has emphasised the need to develop not merely national capabilities assigned through NATO targets, but also pan-European capabilities, particularly strategic enablers that currently depend heavily on the United States: strategic airlift, air-to-air refuelling, missile defence, space-based intelligence and command-and-control capabilities.[14]

In this context, instruments such as the European Defence Industry Programme (EDIP), introduced at the end of 2025, and its flagship defence projects are potentially transformative. Joint projects such as the European Air Shield and the European Drone Defence Initiative can concretely strengthen the European pillar through the joint development of critical capabilities, limiting external dependence while fostering industrial cohesion and interoperability.[15] In certain areas, such as counter-drone systems, US technological maturity is not necessarily dominant, and the operational requirements are evolving quickly. This opens space for European technological leadership, potentially avoiding the emergence of structural dependence.

In this regard, the economic dimension is fundamental. Increases in national defence budgets, the approval of European programmes such as the Security Action for Europe (SAFE) and flexibility regarding military spending within the EU’s 3 per cent deficit threshold are clear prerequisites in creating the conditions for strengthening the European pillar.[16] However, caution is warranted: increased investments in Europe are only a prerequisite. If new resources are absorbed into national procurement, fragmentation will increase and dependence on the United States will remain high. The issue is not only quantitative, that is, burden sharing, but qualitative: which strategic capabilities to develop, and to what degree of integration.

The posture of the Trump administration on defence industry issues introduces an additional ambivalence. On the one hand, Washington calls on Europeans to spend more to take responsibility for Europe’s defence; on the other, it expects that much of this strengthening will occur through increased purchases of US equipment.[17] Furthermore, an additional complication arises from the impact that military operations such as the one currently underway in Iran have on the delivery of the very American systems that Trump is urging Europeans to purchase. The need for the United States to deploy these weapons and ammunition against Iran has a negative impact on the timeframe within which the European countries that have made these purchases will receive their deliveries.[18] This, in turn, generates further mistrust in Europe concerning the reliability of both US supplies and the American security umbrella.

Here lies a structural tension: strengthening the European pillar also means developing an increasingly autonomous industrial base, but without alienating US military support to Europe. In the short to medium term, Europeans cannot operate without certain American strategic enablers. For this reason, the objective cannot be to “emancipate” themselves from the United States, but rather to become indispensable, or at least more important, in Washington’s eyes, transforming dependence into interdependence. A strong European pillar must make Europe a credible military interlocutor capable of assuming primary responsibility in the event of a crisis on the continent, and therefore more influential in the changing transatlantic relations.

From dependency to interdependency: The path to readiness and relevance

A scenario in which Russia decides to test Article 5 during a phase of gradual US disengagement and still incomplete European capability development represents a concrete possibility, as highlighted by the intelligence services of several European countries.[19] It is plausible that a Trump administration decision on how to respond to a Russian attack would not be immediate, but embedded in a negotiating logic aimed at extracting benefits from European interlocutors and/or Russia. In such a critical contingency, the readiness of the European response would be decisive, not only militarily, but politically: to withstand Russian escalation and to signal to Washington that Europe is a responsible and militarily capable actor worthy of support and less vulnerable to pressures.

Strengthening the European pillar of NATO means recognising the evolution of the transatlantic relationship towards a more transactional approach and a more limited US support, and adapting the European posture and might accordingly. It requires greater and shared European responsibilities within NATO, investment in common capabilities and human resources, greater EU-NATO coordination and an increase in industrial production capacity, while bearing in mind that for Europe the Russian threat remains the priority. A European pillar is not an alternative to NATO; on the contrary, it is a conditio sine qua non for preserving the Alliance’s credibility, effectiveness and usefulness in a more uncertain international security environment.


Nicolò Murgia is a Junior Researcher in the “Defence, security and space” programme at the Istituto Affari Internazionali (IAI).

[1] Franke, Benedikt (ed.), Munich Security Conference 2025: Speech by JD Vance and Selected Reactions, Hamburg, Mittler, 2025, https://securityconference.org/en/publications/books/key-speeches-volume-ii-jd-vance-msc-2025.

[2] White House, National Security Strategy of the United States of America, November 2025, https://www.whitehouse.gov/wp-content/uploads/2025/12/2025-National-Security-Strategy.pdf.

[3] Edwards, Christian, “Europe Didn’t Want an Iran War, Yet Trump Is Saddling It with the Consequences”, in CNN, 2 April 2026, https://edition.cnn.com/2026/04/02/europe/europe-nato-iran-war-trump-consequences-intl.

[4] Irish, John and Steve Holland, “Trump Threatens NATO Exit, Scaling Up Tensions with Allies”, in Reuters, 1 April 2026, https://www.reuters.com/business/aerospace-defense/trump-threatens-nato-exit-scaling-up-tensions-with-allies-2026-04-01.

[5] Lister, Tim, “The Loss of 5,000 US Troops in Germany Is Just the Tip of the Challenge Facing Europe”, in CNN, 3 May 2026, https://edition.cnn.com/2026/05/03/europe/germany-trump-troops-europe-intl.

[6] NATO, European Allies to Take on New Leadership Roles in NATO’s Command Structure, 6 February 2026, https://www.nato.int/en/news-and-events/articles/news/2026/02/06/european-allies-to-take-on-new-leadership-roles-in-natos-command-structure.

[7] Hartog, Eva, “We Don’t Know what Trump Wants from Us, Estonia’s Defense Minister Protests”, in Politico EU, 1 April 2026, https://www.politico.eu/?p=8210024.

[8] Erlanger, Steven, “What Europe Learned from the Greenland Crisis”, in The New York Times, 24 January 2026, https://www.nytimes.com/2026/01/24/world/europe/sovereignty-european-union-nato.html.

[9] Edwards, Christian, “Trump Angers Allies with Claim NATO Troops ‘Stayed a Little Back’ from Front Lines in Afghanistan”, in CNN, 23 January 2026, https://edition.cnn.com/2026/01/23/world/trump-nato-afghanistan-frontlines-intl.

[10] Gardner, Andrew, “Freedom is Not Free, Obama Tells Europe”, in Politico EU, 26 March 2014, https://www.politico.eu/?p=145289.

[11] Lunday, Chris et al., “France and Germany’s Next-Generation Fighter Jet Project Is ‘Dead’”, in Politico EU, 6 February 2026, https://www.politico.eu/?p=7899219.

[12] Murgia, Nicolò, “Sfide e interrogativi della coalizione dei volenterosi”, in AffarInternazionali, 19 February 2026, https://www.affarinternazionali.it/?p=116139.

[13] France and UK, Joint Statement by President Macron and Prime Minister Starmer, Co-chairs of the International Summit on the Strait of Hormuz, 17 April 2026, https://www.elysee.fr/en/emmanuel-macron/2026/04/17/joint-statement-by-president-macron-and-prime-minister-starmer-co-chairs-of-the-international-summit-on-the-strait-of-hormuz.

[14] European Commission, Commissioner Kubilius’s Speech at the European Defence Agency Annual Conference, 22 January 2025, https://ec.europa.eu/commission/presscorner/detail/en/speech_25_313.

[15] Murgia, Nicolò and Alessandro Marrone, “The European Defence Industry Programme: The Last Piece of the EU Defence Puzzle?”, in IAI Briefs, No. 26|02 (February 2026), https://www.iai.it/en/node/21481.

[16] European Commission website: Acting on Defence to Protect Europeans, https://commission.europa.eu/node/37191_en.

[17] Kayali, Laura, “Pentagon Aggressively Lobbies EU against Buy European Weapons Push”, in Politico EU, 19 February 2026, https://www.politico.eu/?p=7969080.

[18] Adamowski, Jaroslaw, “Baltic Nations Brace for Impact of Iran War Delaying US Weapons Shipments”, in Defense News, 20 April 2026, https://www.defensenews.com/global/europe/2026/04/20/baltic-nations-brace-for-impact-of-iran-war-delaying-us-weapons-shipments.

[19] Nöstlinger, Nette, “German Spy Chief: Russia Could Test NATO Loyalty to ‘Mutual Defense’ Clause”, in Politico EU, 28 November 2024, https://www.politico.eu/?p=5791815.