Michelle Haas is a PhD Researcher at Ghent University

Tim Haesebrouck is an Assistant Professor at Ghent University

America’s intention to withdraw troops from the continent has left Europe suspended in uncertainty. But instead of waiting for concrete plans, Europe should be proactive in preparing for the inevitable.

At the end of October 2024, just weeks before Donald Trump was re-elected as president of the United States (U.S.), we visited NATO forces in Romania during the large multinational exercise ‘Dacian Fall’. While speaking with a group of U.S. soldiers, we asked about the possibility of a U.S. withdrawal from Europe ahead of next year. They assured us that American troops would not leave Europe. One year later, after ten intense months of Trump’s second presidency, the U.S. announced that it would withdraw 800 troops from Romania, a move that may mark the first step in a broader U.S. pullback from the continent.

In the press release accompanying the announcement, the U.S. Army stressed that “this [withdrawal] is not an American withdrawal from Europe or a signal of lessened commitment to NATO and Article 5. Rather, this is a positive sign of increased European capability and responsibility.”[1] The central question, however, is whether Europe is in fact prepared for a further U.S. drawdown. Simulations and military analyses consistently show that European states would struggle to defend themselves against Russia without substantial American support.[2]

Europe’s recent White Paper on Defence recognizes the risk of a faster U.S. disengagement, noting that the U.S. is  “shifting its focus away from Europe to other regions of the world. This is something we have long been warned about, but which is now happening faster than many had anticipated.”[3] Yet despite this awareness, a coherent European plan for a possible U.S. withdrawal seems to be lacking.

Lessons learned from Ukraine

Europe could draw important lessons from the US’ shifting position to Russia’s war against Ukraine. Although Ukraine is neither a formal U.S. ally, nor protected under Article 5, the Biden administration provided extensive support after Russia’s full-scale invasion, more than €20 billion in annual military aid, along with indispensable intelligence assistance.[4] After Trump returned to power, no new packages were approved. Even previously authorized assistance and intelligence cooperation were briefly suspended. Yet U.S. support did not disappear completely. Intelligence cooperation continued, and the Trump administration approved the PURL initiative, allowing European countries to purchase U.S. military equipment. American aid was reduced, but not cut off.

Ukraine, for its part, has taken significant steps to reduce its U.S. dependence. President Zelensky announced that Ukraine aims to produce 50 percent of the weapons used at the front domestically by the end of 2025, [5] a goal that seems to be reached.[6] The country has already achieved major milestones, including being nearly self-sufficient in the production of drones. According to a report of the Snake Island Institute, a Ukrainian defense think tank, the domestic industry is able to produce up to 10 million drones a year. However, this should also be nuanced, as the external dependency on China could become increasingly problematic. Another example is the development of its own long-range cruise missile, the P-5 Flamingo, with a range of roughly 3,000 km, capable of striking deep into Russian territory.[7] Although the actual development speed of these missiles remains unclear, it still shows how Ukraine is increasingly adapting to a more self-reliant reality.

Critical dependencies remain

These developments suggest that Ukraine will likely be able to continue fighting even without substantial U.S. support. Yet Trump’s attempts to rapidly negotiate a peace deal generated deep concern in both Kyiv and European capitals. Since the beginning of his term, Washington appeared more open to Russia-leaning peace proposals, causing unease in Europe and complicating diplomatic efforts. This anxiety reflects the reality that Ukraine still relies on U.S. weapon sales and intelligence, even if its dependency is gradually decreasing.

Europe also attempted to compensate for diminishing U.S. support. In the first months of Trump’s second presidency, European countries more than doubled their military aid to Ukraine, leading to higher average monthly assistance during the first half of 2025. By the summer, however, European support had dropped back to pre-Trump levels despite the PURL initiative, raising concerns about the long-term sustainability of Europe’s commitment to offset a potential American withdrawal.[8] Moreover, European countries remain unable to completely replace U.S. intelligence support, which continues to constitute a critical dependency for Ukraine.

The Ukrainian experience shows that a U.S. withdrawal is unlikely to be absolute and that even in periods of political tension, certain forms of cooperation, such as intelligence sharing or procurement frameworks, can persist. At the same time, Ukraine illustrates the importance of preparing for uncertainty and reducing strategic dependencies. Lastly,  the war against Ukraine highlights that Europe remains unable to fully compensate for a significant U.S. withdrawal, making the absence of European planning even more challenging.

Planning for US withdrawal

Recent initiatives, from the EU’s White Paper for Defence to rising military budgets and more ambitious capability targets, show that Europe is increasingly preparing itself to assume greater responsibility for its own defense.[9] However, these efforts still lack an essential element: a coherent and realistic plan for how Europe should respond if the U.S. reduces its military presence on the continent. NATO’s Defense Planning Process assumes continued U.S. capabilities, while EU mechanisms have little influence on national planning and exclude the United Kingdom.

Any effective planning process must begin with a better understanding of what a U.S. retrenchment might look like. Currently, Europe is left in the dark, as the Global Posture Review of the Pentagon is yet to be finalized, and the Trump administration is not communicating about what to expect. At the same time, Europe’s defense is still depending on roughly 80,000 U.S. servicemembers stationed on the continent, crucial for Europe’s reinforcement strategy, infrastructure networks, military enablers, ISR capabilities and overall regional defense.[10]

A complete American withdrawal remains improbable. The U.S. strategic interests[11] in Europe endure: its military bases and access to European airspace and waters are essential for Washington’s global military reach. Europe is also a vital economic partner and an important market for the U.S. defense industry. More generally, a cohesive Western alliance continues to strengthen America’s global position: the U.S. needs reliable partners to address contemporary security challenges, from counterterrorism to the managing its relations with countries like Iran and China. Moreover, the decision to not maintain the rotational U.S. brigade in Romania has already spurred criticism among the Republican family. This illustrates that political consensus on a full U.S. withdrawal is absent.[12]

Wide spectrum of scenarios

Yet it is equally unlikely that nothing will change. The October 2025 announcement of withdrawal from Romania reflects a long-term shift. Since the end of the Cold War, the strategic logic that once bound U.S. and European security so closely together has weakened. With the collapse of the Soviet Union, Europe ceased to be the decisive theatre for American power, and attention gradually shifted toward other regions. The Obama administration’s “pivot to Asia” formalized this shift, and even though recurrent crises temporarily pull U.S. forces back to Europe, the structural trend is one of gradual reduction.[13]

Between the extremes of full withdrawal and business-as-usual lies a wide spectrum of scenarios. Some analysts envision the U.S. as a ‘balancer of last resort’,[14] intervening only when Europe faces an existential threat. Others suggest that the U.S. could limit itself to providing intelligence, naval power and nuclear deterrence, while leaving most conventional defense to Europeans.[15] Still others argue for maintaining a more substantial U.S. footprint, yet even these proposals involve reductions and a reallocation of assets to the Indo-Pacific.[16] The common denominator is clear: Washington will expect Europe to assume far greater responsibility for its own defense. Yet Europe is still reluctant to accept this near-future reality.

A more mature transatlantic partnership

The uncertainty of US withdrawal from Europe makes planning even more, not less, essential. The objective is not to detach Europe from the U.S., but to negotiate a phased and mutually agreed division of labor within NATO. Such a roadmap should identify which U.S. capabilities will remain essential, which can be reduced, and which must be replaced by European forces. A proactive European position would strengthen NATO’s deterrence posture, reduce costs and risks for Washington, and give Europe a stronger bargaining position within the alliance. Most importantly, it would ensure that Europe shapes the transition, rather than being forced to react to it.

Ukraine has shown that reduced U.S. engagement does not necessarily mean complete abandonment, but it also demonstrates the limits of European compensatory capacity and the perils of excessive dependence. Precisely because the U.S. is unlikely to withdraw completely, Europe has an opportunity to negotiate a balanced division of labor before decisions are imposed unilaterally by Washington. Europe needs a readable US policy, with a clear timeline on what to expect. Rather than waiting for this to materialize, the continent can take proactive steps toward a more strategically mature transatlantic partnership.

[1] https://www.europeafrica.army.mil/ArticleViewPressRelease/Article/4326550/press-release-department-of-war-announces-change-to-army-unit-rotation-in-europe/

[2] https://www.iiss.org/research-paper/2019/05/defending-europe/

[3] https://commission.europa.eu/document/download/e6d5db69-e0ab-4bec-9dc0-3867b4373019_en

[4] https://www.kielinstitut.de/publications/news/ukraine-support-europe-could-replace-most-of-the-us-support

[5] https://www.president.gov.ua/en/news/volodimir-zelenskij-na-kinec-roku-ne-mensh-nizh-50-zbroyi-na-100633

[6] https://www.reuters.com/business/aerospace-defense/zelenskiy-says-nearly-60-ukrainian-arms-home-produced-2025-09-06-

[7] https://www.iiss.org/online-analysis/missile-dialogue-initiative/2025/09/ukraines-flamingos-take-to-the-skies/

[8] https://www.kielinstitut.de/publications/news/ukraine-support-tracker-military-aid-falls-sharply-despite-new-nato-initiative/

[9] https://www.sampol.be/2025/04/naar-een-sterke-europese-defensie-zonder-europees-leger

[10] https://www.csis.org/analysis/how-europe-can-defend-itself-less-america

[11] https://www.foreignaffairs.com/europe/beware-europe-you-wish-wallander

[12] https://armedservices.house.gov/news/documentsingle.aspx?DocumentID=6346

[13] https://www.atlcom.nl/magazine/wat-betekent-amerikas-nieuwe-defensiestrategie-straks-voor-europa/

[14] https://foreignpolicy.com/2025/08/22/us-withdrawal-troops-europe-defense-realism/

[15] https://www.foreignaffairs.com/europe/best-nato-dormant-nato

[16] https://www.foreignaffairs.com/united-states/how-us-forces-should-leave-europe

Photos: U.S. Department of War