US Influence on European Defence Policy

US commitment and influence on the development of European defence policy

1. Introduction

Since the end of World War II, the United States has played a crucial role in the development and security of Europe. From the establishment of NATO in 1949 to modern strategic partnerships, the U.S. has consistently demonstrated its commitment to European stability through military alliances, economic aid and cooperative defence initiatives. This long-standing partnership has evolved in response to global threats, geopolitical shifts, and technological advancements. The future of European defence will likely involve a blend of deeper EU collaboration and continued reliance on NATO, with entities adapting to the changing global dynamics and ensuring that Europe remains secure in the face of emerging threats.

Russia’s aggression in Ukraine has brought the largest war to Europe since 1945. Russia’s actions, along with Chinese assertiveness, questions around American leadership, political discontent throughout the West, and much else besides, have weakened the international order and impacted transatlantic relations.

This article aims to explore the trajectory of U.S. support for European defence, highlighting key milestones, challenges and the ongoing importance of transatlantic security cooperation and European defence policy development.

We will begin with an overview of the American impact on the development of European policy in recent years, before looking at present developments and, finally, future prospects. These approaches will give us a better understanding of some of the issues at stake in the development of European security policy.

1. Historic cooperation

The devastation of the Second World War has been a cornerstone of European security and defence. The devastation of the war left Europe vulnerable, prompting the U.S. to take an active role in rebuilding and safeguarding the continent. They played a leading role in establishing the Marshall Plan (1948) to provide economic assistance to war-torn European nations to promote recovery and prevent the spread of communism. In 1949, under president Truman, the creation of the North Atlantic Treaty Organisation (NATO) provided a collective defence framework, pushing European nations to rearm and helping them to develop a collective defence mindset. The deployment of U.S. troops in Europe and the establishment of military bases further solidified this commitment. The US leadership in NATO helped European forces adopt standardised training, equipment and logistics, improving the ability of European militaries to operate together. For Europeans, NATO guarantees collective security, but it is accompanied by strong American leadership. This dependence, accepted out of necessity, nevertheless hampered the first attempts at autonomous European defence. The failure of the European Defence Community (EDC) in 1954 illustrates these internal contradictions, but also the difficulty for Europe to organise itself outside American influence. US influence has imposed itself as a structuring framework, but also as a constraining one: national defence policies remain aligned with Washington’s priorities, and European initiatives struggle to emerge. The strategic balance clearly rests on the commitment of the United States.

After the Cold War, Washington played a key role in trying to convince European nations to invest more in their own defence. Instead of disengaging, the US led NATO interventions in Bosnia (1995) and Kosovo (1999), which helped to reinforce commitment to European stability. They helped Europeans to modernise and expand their military capabilities, invest in their defence infrastructure and reinforce the importance of high-tech military advancements. In maintaining military bases in Europe, the U.S. facilitated joint military exercises, which improved European defence readiness and cooperation.

Europe invested in its own security. In 2017, especially, the European Security and Defence Policy (ESDP), the European Union's instrument for security policy, was created. This policy was cautiously supported by the United States and initially conceived as a complement to NATO, not in competition with it. The Europeans then felt a contradictory injunction: to be more responsible without questioning American leadership.

The invasion of Iraq in 2003, decided unilaterally by the United States, created a rift within Europe and with Washington. Some Europeans criticised American policy, while a debate began on the need for European strategic autonomy. Despite this, NATO remained the dominant architecture. European dependence on American resources was flagrant, especially in areas such as intelligence, air defence systems, etc. For many Europeans, autonomy remained a distant ideal.

In response to Russia’s annexation of Crimea in 2014, and more importantly, the war since 2022, the U.S reinforced its military presence in Eastern Europe. Their commitment reinforced the idea that European security still depends on U.S. military power. While the U.S. wants Europe to take more responsibility, Washington has increased its military presence in response to Russian threats. They continued to push for European allies to meet the NATO defence spending target of 2% of GDP. This pressure has led to increased investments in European defence capabilities, with countries like Poland and the Baltic states having gone beyond 2% after 2023. Under the first Trump presidency (2017-2021), the redeployment of US troops raised concerns about US reliability, influencing European defence policy discussions on independence.

In other words, Russia’s war against Ukraine has revealed the deplorable state of Europe’s armies and defence industries after decades of peace dividends, and their deep dependence on the United States.

2. Current development and political shift

The US commitment to deterrence, particularly against Russia, influences European defence spending and military strategy. Currently, the European dependence on the United States in terms of defence remains strong. The Draghi Report, published in September 2024 by the EU Commission, shows that 78% of the weapons purchased by EU member states were coming from outside Europe, with 63% coming from the United States.

The new Trump administration signalled a decreased commitment to NATO in the last months, with Defence Secretary Pete Hegseth suggesting a reduction in U.S. troops stationed in Europe. This move indicates a strategic pivot, urging European allies to take greater responsibility for their own security. In a notable policy shift, President Trump engaged directly with Russian President Vladimir Putin, including a summit in Riyadh on February 18, 2025, to discuss the Ukraine conflict. Notably, Ukrainian and European representatives were excluded from these discussions, raising concerns among European leaders about being sidelined in critical matters.

The European Union reacted in an unprecedented way. The EU is already gradually putting in place and accelerating the functioning of instruments to structure its defence policy. Among other things, the Strategic Compass (2022), for example, is an ambitious policy document setting out defence and security priorities up to 2030; the creation of the Rapid Deployment Capacity (planned for 2025) with the capacity to deploy up to 5,000 soldiers for crisis operations.

For the first time, the Union has financed the purchase and delivery of arms to a country at war through the “European Support Fund for Ukraine”. Defence budgets have been significantly increased: many Member States, starting with Germany (with its 100 billion euro fund), have taken measures to increase their military capabilities. Industrial cooperation initiatives have also been stepped up, with joint projects on ammunition production, air defence and the future Franco-German tank (Main Ground Combat System).

In response to the shifting US stance, European nations increased mechanisms of dialogue. The Weimar+ alliance, for example, was formed in February 2025, expanding the original Weimar Triangle (France, Germany, Poland) to include in discussions the United Kingdom, Spain, Italy and the European Commission. This alliance aims to promote European sovereignty and coordinate defence efforts independent of US influence.

Despite all of these evolutions, key challenges are preventing the development of common policies and initiatives. Europe's defence industry is too fragmented, needs to achieve greater coherence between its defence programmes, standardise its processes and needs more financial resources. The Draghi Report argues that “Europe’s defence industry remains insufficient to meet emerging security threats”. Among other things, the report called for a radical transformation of the EU’s government financing model, arguing that insufficient public and private investment has led to a spending gap of approximately five per cent of the EU’s GDP per year.

In March 2025, the European Commission revealed a plan called “ReArm Europe” consisting of height hundred billion euros in additional defence investments to address the next decade gaps exposed by the war in Ukraine and to prepare for future security challenges. This plan recommends this level of expenditure, but at present, no funding has been secured. To facilitate investments, the European Commission also proposed to activate the national escape clause of the Stability and Growth Pact, allowing member states to increase their defence spending up to 1.5% of GDP per year for four years, without violating the EU’s budgetary rules. These exceptional plans should have direct consequences on the ability of states to invest in their national defence. The impact of these plans remains to be determined and discussed. States like France or Italy can't afford much higher deficits and are thus proposing to take on collective debt as EU member states. However, states such as Germany or the Netherlands were opposed in the past to such a mechanism. This rift in financial resources could prove to be a key issue in European rearmament.

On another level, the US continues to support a large number of EU initiatives, such as the European Deterrence Initiative (EDI), created right after the annexation of Crimea. They expanded their participation in joint exercises and the creation of infrastructure to enhance European defence readiness. They provided advanced weapons systems to European allies, including F-35 fighter jets, Patriot missile systems, and tanks. They are also supporting regional European security initiatives such as the French-led European Intervention Initiative (EI2), which aims for rapid crisis responses without NATO involvement.

In a nutshell, the deteriorating European security environment and the changing priorities of the United States mean that Europe must be prepared to assume greater responsibility for its own defence. Europeans require a sustained plan that combines immediate efforts to support Ukraine and rebuild readiness, and long-term goals to develop a “full force package”, including the combat support capabilities and key enablers that are currently provided primarily by the US.

3. Future perspectives: Towards American uncertainty and European strategic autonomy

As seen previously, in the last few years, the U.S. has encouraged European nations to take greater responsibility for their security while reinforcing NATO’s role. However, the degree to which Washington supports European strategic autonomy (e.g., EU defence initiatives) depends on geopolitical developments.

The U.S. remains the leading force in NATO, providing military capabilities, intelligence, and nuclear deterrence. However, the commitment to NATO’s deterrence and defence posture is likely to fluctuate as successive administrations reassess the extent of US involvement. Donald Trump has already openly questioned the nuclear umbrella over eastern European states, thereby significantly weakening the credibility of NATO Article 5.

Two major issues will continuously be evaluated for the next months and years: The need to build a European pillar within NATO, and the need to create a continental defence technological and industrial base (DTIB).

On their own, European countries are significantly boosting their defence budgets. Denmark announced an increase to 3% of its GDP for defence, and Estonia plans to allocate over 4% by 2026. These measures reflect a collective effort to enhance military capabilities amid concerns over reduced US support.

A commitment to maintain a high level of effort for as long as necessary will be essential for rebuilding European militaries. A comprehensive, scenario-based study by the International Institute for Strategic Studies (IISS) in 2019 estimated that European countries “would need to invest up to $357 billion to build a force capable of addressing a serious Article 5 contingency” in the Baltic region, without significant U.S. support. While the lessons learned from Ukraine will influence the precise amount required, this figure highlights both the scale of the effort and the fact that it remains achievable. European nations are already spending over $100 billion more per year than they were in 2019. The critical challenge lies in maintaining this sustained effort over the long term to build and sustain the necessary capabilities, ensuring a capable and ready force model over time.

Furthermore, it will be a challenge to demonstrate the EU’s capacity to coordinate defence industrial decisions, while ensuring that military planning remains within the purview of member states and NATO. While NATO leads in defence planning and resource allocation, it does not manage procurement. The European Union, on the other hand, plays an economic role, including coordinating defence spending across member states. The key challenge will be synchronising NATO strategic planning with the EU’s defence spending decisions, ensuring that Europe develops a more self-sufficient and competitive defence sector while maintaining transatlantic cohesion.

Early in 2024, the EU released the European Defence Industrial Strategy (EDIS), which aims to strengthen the European defence technological and industrial base (EDTIB). EDIS sets out a vision for the EU’s defence policy through 2035. In theory, the goal is to produce more, quicker. In reality, it means that by 2030, intra-EU defence trade should represent at least 35 per cent of the value of the EU’s defence market and at least 50 per cent of member states’ defence procurement should be procured from the EDTIB (with 60 per cent by 2035). According to Andrius Kubilius, European Commissioner for defence and Space and the defence industry will have to evolve significantly in the next years, member states ‘need investment and financing capacity, and the President’s announcements are a first step’, referring to the 800 billion ‘ReArm Europe’ programme announced at the beginning of March by Ursula von der Leyen. For Andrius Kubilius, it is necessary to ‘invest more, invest better, invest European’.

In short, to achieve significant policy progress, Europeans need to focus on a short list of priorities - ranging from immediate objectives to long-term efforts to addressing capability gaps and fixing organisational challenges - to prepare for the future without dodging some of the difficult debates. As seen, European defence industries are struggling to meet demand and deliver within a reasonable timeframe. To this end, the EU aims at mobilising its toolbox to structure the European defence technological and industrial base and support joint acquisitions.