The Changing Transatlantic Relationship
The transatlantic alliance has long been the bedrock of European security. However, recent events have exposed deep fissures in this once rock-solid partnership. The seismic shift in U.S. foreign policy under President Trump, amplified by Vice President J.D. Vance’s stark remarks at the Munich Security Conference, has signalled a stark departure from the era of American-led global security. The public falling-out between Presidents Trump and Zelensky in Washington only solidified the notion that America’s commitment to leading the free world has diminished. As the U.S. signals its reluctance to continue as Europe’s security guarantor, European leaders have acknowledged the urgent need for strategic autonomy. German opposition leader Friedrich Merz has stressed that Europe must become independent from the U.S., while European Commission President Ursula von der Leyen has called for rearmament. French President Emmanuel Macron has long championed a European force capable of ensuring the continent’s security. This newfound urgency has revived discussions on the creation of a European army, a concept long deemed politically and legally complex. Yet, beyond rhetorical commitments, the path to achieving this goal presents three critical dilemmas: Should such a force complement or replace national armies? Should its governance be intergovernmental or supranational? And should participation be mandatory or voluntary?
The Historical Context: European Defence Cooperation and Its Failures
Europe’s history with collective defence is marked by ambition and failure. In the 1950s, the European Defence Community (EDC) promised full military integration but was ultimately blocked by the French Parliament over concerns about sovereignty. Since then, Europe’s security has remained largely dependent on NATO, with the U.S. providing the bulk of military deterrence and rapid response capabilities. Europe’s inability to act autonomously in crises has been starkly evident. During the Yugoslav Wars of the 1990s, Europe’s military inefficacy was laid bare, requiring U.S. intervention to bring the conflict to an end. In 2011, European powers failed to enforce a no-fly zone over Libya without significant American support. The 2021 evacuation of Kabul further underscored Europe’s reliance on U.S. military logistics and strategic enablers. Despite this reliance, the European Union has made some strides toward defence integration. Since 2017, the Permanent Structured Cooperation (PESCO) framework has facilitated collaboration among Member States on defence projects. The European Peace Facility has been used to finance arms deliveries to Ukraine, and initiatives like the European Defence Industry Reinforcement through Common Procurement Act (EDIRPA) aim to streamline collective defence procurement. Additionally, the European Union Military Assistance Mission (EUMAM) has provided direct support for Ukrainian forces. However, while the EU has laid the groundwork for cooperative defence structures, it lacks the legal and institutional mechanisms for autonomous territorial defence. The core question remains: Can the EU move beyond fragmented cooperation to establish a credible European army?
Legal Constraints: The Limits of the EU Treaties
The European Treaties pose significant legal constraints on the establishment of a European army. While Article 42(2) of the Treaty on European Union (TEU) vaguely refers to the possibility of a common defence, enacting such a framework would require Treaty amendments and, in some cases, constitutional changes in Member States. The mutual defence clause in Article 42(7) TEU, often compared to NATO’s Article 5, is also limited in scope, as it obliges Member States to assist each other rather than committing the EU itself to territorial defence. Moreover, existing EU military structures are designed primarily for crisis management beyond EU borders rather than territorial defence. While the Military Planning and Conduct Capability (MPCC) provides some strategic oversight, it lacks the operational strength required for large-scale military deployments. The recently established Rapid Deployment Capacity (RDC), which evolved from the EU Battlegroups concept, could serve as a stepping stone, but it remains far from a comprehensive European military force. To overcome these legal barriers, European leaders must navigate three fundamental dilemmas that will shape the future of European defence integration.
Dilemma 1: Complementary or Substitutive Armed Forces?
A fully integrated European army, replacing national militaries under a centralised command, is politically and practically infeasible. National governments are unlikely to cede sovereignty over their military forces to an EU-led command structure. Article 4(2) TEU explicitly designates national security and territorial defence as core responsibilities of Member States, making full integration legally unattainable without treaty revisions. A more pragmatic approach would be the creation of a complementary force that enhances existing national capabilities. Europe lacks critical military enablers—strategic airlift, satellite reconnaissance, and cyber defence—rather than troops or tanks. By pooling resources, an EU-led force could fill these gaps without undermining national militaries. Frontex, the EU’s border agency, provides a useful institutional model. Initially a coordination mechanism, Frontex gradually expanded its mandate, acquiring its own personnel and resources without requiring treaty amendments. A similar incremental approach to defence integration could allow for the development of shared military assets, such as transport fleets, intelligence-sharing frameworks, and centralised stockpiles of critical resources. Such a strategy would enhance Europe’s collective security without the political roadblocks associated with full integration.
Dilemma 2: Intergovernmental or Supranational Governance?
The EU’s current defence decision-making is intergovernmental, requiring unanimous approval from Member States. While this preserves national sovereignty, it often leads to deadlock. The intergovernmental nature of EU defence stems from the post-World War II compromise that separated economic integration (supranational) from security policy (intergovernmental). However, as European security threats mount, this division is becoming increasingly untenable. Moving towards a supranational defence structure would require significant legal changes. For example, Germany’s Federal Constitutional Court has ruled that transferring defence powers to the EU would necessitate both treaty amendments and constitutional revisions. However, there is precedent for exceptional EU-led initiatives within existing treaties. The EU’s pandemic recovery fund, NextGenerationEU, was a temporary measure that allowed the bloc to raise debt collectively, blending intergovernmental and supranational elements. A similar model could be applied to defence, creating an EU military force within an intergovernmental framework but with structured oversight by the European Parliament.
Dilemma 3: Mandatory Participation or a Coalition of the Willing?
The final challenge is determining whether participation in a European army should be mandatory for all Member States or limited to a voluntary coalition. A mandatory structure would ensure uniformity but faces significant political resistance, particularly from neutral states such as Ireland, Austria, and Malta. A coalition of the willing would allow ambitious states to move forward without being hindered by reluctant partners. This approach is already used in PESCO and aligns with the direction proposed in the EU’s 2022 Strategic Compass. However, relying on voluntary participation risks fragmentation, weakening Europe’s collective deterrence capability. To mitigate this, any coalition should be institutionalised within the EU framework, allowing other states to join seamlessly. This would preserve the bloc’s unity while enabling rapid progress in defence integration.
The Road Ahead
If the current geopolitical climate fails to prompt EU Member States to deepen defence integration, what will? The crisis in Ukraine and the shifting transatlantic relationship have made it clear that Europe can no longer rely solely on the U.S. for security. The debate over a European army is not just about military capabilities—it is about Europe’s diplomatic weight in an increasingly multipolar world. The most feasible path forward is a complementary force, governed through an intergovernmental framework, and initially driven by a coalition of willing states. However, defence unanimity requirements remain a significant obstacle. Introducing qualified majority voting in certain defence matters—paired with strong parliamentary oversight—could make EU defence policy more agile. The coming years will reveal whether European leaders are ready to make the difficult choices required to achieve strategic autonomy. But as the global order shifts, Europe’s window of opportunity is closing fast.
