Scenario Analysis: U.S. Withdrawal from NATO and Europe
The U.S., as NATO’s largest military contributor, plays a critical role in the Alliance’s deterrence and defense posture. A reduction or complete withdrawal of U.S. forces from Europe would weaken NATO’s capabilities, reshape European security dynamics, and force European nations to rethink their defense strategies and alliances.
If the U.S. decides to reduce its troop presence in Europe, even partially, this would pose security risks, particularly for Poland and the Baltic states[1]. Right now, Russia is too busy with Ukraine. However, in the longer term, with Russian efforts to increase its military presence in Belarus, it will be more likely that these countries will be exposed to Russian aggression. Smaller nations like Estonia, Latvia, and Lithuania rely heavily on U.S. military presence for deterrence, air defense, and rapid response capabilities. However, the problem is Europe-wide. All European NATO members depend strongly on the U.S. for logistics, intelligence, and advanced military systems, such as missile defense capabilities, which are difficult to replace or step up in the short term[2]. A possible outcome, therefore, is that the multilateral relations become less important. European states might seek bilateral defense agreements with Washington to maintain protection outside NATO’s multilateral framework[3].
A complete U.S. exit from NATO would have severe financial and military consequences for the Alliance and for Europe. NATO’s budget would shrink dramatically, from $1,200 billion to $400 billion[4]. Troop numbers would drop from 3.5 million to 2 million[5]. This shows a significant decrease in the Alliance’s capacity. The nuclear deterrent would also be weakened, as only the UK and France are European nuclear powers, with a combined total of 515 nuclear warheads. Compared to Russia’s 5,889, this results in a strong imbalance[6]. The weakening capacity of NATO that may follow after the U.S.’s full withdrawal would put immense pressure on big military powers like Germany, France, and the UK to take the leadership in European defense to restore and maintain credible deterrence. However, with the multilateral arrangements possibly getting weaker, NATO could fragment, with members seeking bilateral security agreements with Washington instead.
Regardless, the U.S. has become a less reliable ally to Europe than at any time since the end of World War II. Therefore, Europe must accelerate the development of an independent defense structure, for example, through EU-led defense initiatives or even a common EU army. This could also include redirecting frozen Russian assets to fund aid to Ukraine and military expansion across Europe. Europe must invest more in air defense and long-range strike capabilities. It must strengthen regional defense cooperation, coordination and logistics. In sum, a European response must be quick, unified and sustainable in order to support Ukraine and counterbalance Russian threats independently from the U.S.. The initiative of the European Commission “ReArm Europe” as introduced on 4 March 2025 is a step in the right direction[7].
Europe’s Weaknesses and Challenges
Europe’s response must be quick, unified and sustainable to act independently from the U.S.. However, it will face significant challenges in doing so. These challenges are mostly structural, political, and logistical and may hinder Europe’s ability to function as a fully independent military power.
One major weakness is the lack of military standardization and interoperability across NATO members[8]. European armies operate a wide range of tanks, aircraft, and weapon systems independently, creating inefficiencies in maintenance, training, and supply chains. This fragmentation extends to command structures, hindering rapid decision-making and effective coordination efforts. Unlike the U.S. and Russia, which can deploy large, unified military units, European forces struggle with interoperability due to differing operational systems and procedures. Additionally, logistical and military mobility challenges and infrastructure limitations hinder Europe’s ability to move troops and equipment quickly across borders. This undermines NATO’s responsiveness to potential threats[9]. In the absence of U.S. logistical support, these issues become even more pressing.
Secondly, while European defense budgets are rising, they still lag behind Russia’s defense spending as a percentage of GDP, leaving European militaries underfunded and unprepared[10]. Europe needs a massive expansion in personnel and equipment. Estimates suggest Europe would require at least 50 new brigades, 1,400 tanks, 2,000 infantry fighting vehicles and 700 artillery pieces to fill the gap without U.S. support[11]. However, scaling up the production of weapons and other military equipment remains a challenge as European defense industries lack the production capacity, especially without the support of the U.S.. This makes it particularly challenging – if not impossible – in the short term to quickly replace equipment losses or stockpile sufficient weapons for credible deterrence or sustained conflict.
Thirdly, internal political divisions further weaken Europe’s ability to coordinate these efforts. Leaders such as Hungary’s Orbán and Slovakia’s Fico, alongside other far-right populist movements in various European countries, form another hurdle to deeper NATO and EU integration and more support for Ukraine[12]. These divisions and disagreements over defense strategy and threat perception lead to NATO fragmentation while a quick, unified, and sustainable European response is needed. These political divisions make a decisive, strong European-led defense initiative more complicated.
The Path Forward: European Ownership For Own Defense
I argue that, in order to effectively respond to the changing world order and European security landscape, Europe must adopt a fundamental shift in its defense mentality. It should immediately move away from reliance on U.S. security guarantees towards a focus on strategic autonomy. Europe needs to think for itself rather than looking at what the U.S. and Russia will potentially do or not do [13]. Increased defense spending and military modernization are essential aspects. But these efforts will be insufficient if Europe’s commitment to collective security is not strong and unified.
The major priority here lies in deepening military coordination, cooperation, and interoperability among European forces. Equipment, communication systems, training exercises, intelligence, and logistical structures need to be standardized and integrated on the European level to enhance Europe’s credible deterrence strategy. Troop deployments on NATO’s Eastern Flank need to be expanded. Political divisions within NATO and the EU need to be addressed, and unity among European allies must be promoted. As the EU High Representative for Foreign Affairs and Security Policy Kaja Kallas stated, “The free world needs a new leader”. It is time for Europe to acknowledge its responsibility for its defense, deterrence, and values. A secure future depends on Europe’s willingness to take ownership of its capabilities. Europe’s mindset must shift away from dependency toward responsibility.
[1] Follorou, J. (2025, 7 maart). What Baltic intelligence agencies say about the risks of peace talks with Russia. Le Monde. https://www.lemonde.fr/en/international/article/2025/03/07/what-baltic-intelligence-agencies-say-about-the-risks-of-peace-talks-with-russia_6738924_4.html
[2] Nieuwsuur. (2025, 22 februari). Wat als Europa zichzelf moet verdedigen? [Video]. YouTube. https://www.youtube.com/watch?v=SkEd4RzV0Pc
[3] Spatafora, G. (2025, 17 februari). The Trump card: What could the US abandonment of Europe look like? European Union Institute For Security Studies. https://www.iss.europa.eu/publications/briefs/trump-card-what-could-us-abandonment-europe-look
[4] NATO Public Diplomacy Division. (2024). Defence Expenditure of NATO countries (2014-2024). https://www.nato.int/nato_static_fl2014/assets/pdf/2024/6/pdf/240617-def-exp-2024-en.pdf
[5] Clark, D. (2024, 3 juli). Number of active military personnel in NATO countries in 2024. Statista. https://www.statista.com/statistics/584286/number-of-military-personnel-in-nato-countries/
[6] ICAN. (2023). Which countries have nuclear weapons? https://www.icanw.org/nuclear_arsenals
[7] Von Der Leyen, U. (2025, 4 maart). Press statement by President von der Leyen on the defence package. European Commission. https://ec.europa.eu/commission/presscorner/detail/sv/statement_25_673
[8] Nieuwsuur. (2025, 22 februari). Wat als Europa zichzelf moet verdedigen? [Video]. YouTube. https://www.youtube.com/watch?v=SkEd4RzV0Pc
[9] Nieuwsuur. (2025, 22 februari). Wat als Europa zichzelf moet verdedigen? [Video]. YouTube. https://www.youtube.com/watch?v=SkEd4RzV0Pc
[10] Mackenzie, L. (2025, 12 februari). Russian defense spending overtakes Europe, study finds. Politico. https://www.politico.eu/article/russian-defense-spending-overtakes-europe-study-finds/
[11] Burilkov, A., & Wolff, G. B. (2025, 21 februari). Defending Europe without the US: first estimates of what is needed. Bruegel. https://www.bruegel.org/analysis/defending-europe-without-us-first-estimates-what-needed
[12] Brzeziński, B. (2025, 2 maart). Orbán and Fico look to derail European unity on Ukraine ahead of London summit. Politico. https://www.politico.eu/article/viktor-orban-robert-fico-derail-europe-unity-ukraine-london-summit/
[13] Nieuwsuur. (2025, 22 februari). Wat als Europa zichzelf moet verdedigen? [Video]. YouTube. https://www.youtube.com/watch?v=SkEd4RzV0Pc