Recently, U.S. Vice President J.D. Vance shocked Europe with his speech at the Munich Security Conference, signalling a diminishing sense of shared values between the U.S. and Europe. This was further reinforced by last Friday’s press conference in Washington, where a row between President Trump and President Zelensky confirmed that America’s commitment as leader of the free world has disappeared. As simultaneously American security guarantees also seem to dissolve, Ukrainian President Volodymyr Zelensky has called for the establishment of a “European army”. Meanwhile, European leaders stressed that Europe must “become independent from the U.S.” (Friedrich Merz), “re-arm” (Von der Leyen) and “define capacity needs for a common defence” (Macron). To realise these aims, the Member States will have to make at least three difficult, fundamental decisions beyond the questions of its legal feasibility under the Treaties. For swift progress, a complementary force involving willing Member States under intergovernmental decision-making appears the most realistic path to achieve common territorial defence, while concerns regarding democratic decision-making remain.
Historical context: European countries and collective defence
European countries have a mixed record in defence cooperation. The 1950s attempt to establish a fully integrated European Defence Community (EDC) failed just before the finish line, when the French Parliament refused to ratify the treaty, fearing a loss of sovereignty. Since then, Europe has struggled with effective defence actions without U.S. support, as seen during the Yugoslav Wars in the 1990s, the 2011 Libya no-fly zone, and the 2021 Afghanistan evacuation.
The continued reliance on NATO masked Europe’s shortcomings. However, with waning U.S. involvement, European countries not only have to compensate through additional defence-spending but also face an urgent need for robust and autonomous institutional structures and decision-making processes to guarantee European territorial defence. While the EU appears to be a logical actor, it is not yet fully equipped for this role.
Since 2017, many concrete steps have been taken towards common defence within the EU, notably through PESCO (Permanent Structured Cooperation) under Article 42(6) TEU. This integration framework enables almost all EU-Member States to collaborate on various defence projects. The war in Ukraine has further accelerated efforts. The European Peace Facility has been used to finance arms deliveries to Ukraine, while programs like EDIRPA (European Defence Industry Reinforcement through Common Procurement Act) aim to coordinate and acquire critical defence materials. Additionally, the EU launched the EU Military Assistance Mission in support of Ukraine (EUMAM) to train Ukrainian forces. In terms of capacities, the EU in 2007 already created EU Battlegroups (EUBG), composed of multinational battalion sized forces, but those troops have never been deployed. Following the 2022 Strategic Compass, the EUBG were transformed into the EU Rapid Deployment Capacity (RDC), a framework of up to 5,000 troops available to swiftly respond to threats and crises outside EU territory.
Legal constraints within the EU Treaties
Despite these developments, the Treaty on the European Union (TEU) offers limited provisions for territorial defence. Article 42(2) TEU abstractly refers to the establishment of a “common defence”, but its conditions are stringent, comparable to a simplified treaty amendment and probably requiring national constitutional changes. Apart from Article 42(2) TEU, a clear legal basis for EU-led territorial defence therefore remains absent.
Article 42(7) TEU includes a mutual defence clause, comparable to Article 5 of the NATO Treaty, but it is addressed to the Member States, not the EU itself. The institutional framework for military operations in articles 42-46 TEU focusses primarily on crisis management missions outside the EU, aimed at stabilization and capacity-building. Examples include EUNAVFOR, which enforces the UN arms embargo on Libya. Such missions require unanimous consent from Member States (Article 42(4) TEU), potentially hindering swift action. Moreover, the EU lacks a true permanent military command structure with sufficient operational strength, complicating joint mission execution. The existing Military Planning and Conduct Capability (MPCC) operates at the military-strategic level but is set up to support (small scale) military missions outside EU territory.
Three dilemmas in designing a European army
Can one solve the above-mentioned problems with the creation of a European army, and under what legal basis? The current and swiftly changing global situation and the limited scope of this piece do not lend themselves to ready-made solutions. Instead, we make a start by pointing out three fundamental dilemmas for policymakers.
Complementary vs. substitutive armed forces
Discussions around a European army often envision fully integrated national forces under a central command. However, this is politically and practically unfeasible, as it would require the political leaders to transfer “their military instruments” to the EU trough a long and costly integration process. Moreover, it would necessitate amendments to the Treaties, as for example article 4(2) TEU defines national security and territorial defence as core responsibilities of Member States.
A more viable approach is a complementary force that enhances national capabilities, such as a shared transport fleet, cyber defence units, or satellite capacities like the Galileo project. After all, compared to the US, the EU Member States do not necessarily lack troops and assets such as tanks but especially these “strategic enablers”. They are expensive, even for large Member States. Complementary EU forces could be a way to pool the resources to develop them. The EU could also establish centralized stockpiles of critical resources, to be “unlocked” for Member States in case of conflict.
This incremental approach could operate within existing Treaties. The aforementioned RDC could serve as a “building block” as it already has completed a degree of integration within the Union’s military and political institutions. Still, the RDC does not qualify as a complementary force since it is still composed of units of the Member States’ military. Frontex therefore serves as a better institutional model. It was initially set up to coordinate national border protection but later granted an expanded mandate, including its own personnel and resources, without requiring treaty changes. Under specific conditions, the Council, on a proposal from the Commission, can even decide by qualified majority to deploy Frontex-operations against the will of the Member State that it regards. This procedure also entails an obligation to inform Parliament.
Intergovernmental vs. supranational governance
Currently, EU defence decisions require unanimous Member State approval, preserving national control but risking deadlock. This framework dates from the idea that, following the demise of the EDC, European economies would be placed under supranational governance of the (now) EU, whilst defence would remain under intergovernmental governance of NATO. Although economic integration has effectuated the EU’s promise (“no more war”), this split between economy and defence has become obsolete as European states themselves have become the target of armed aggression.
Nevertheless, the current legal framework still reflects this split. Moreover, the attribution of territorial defence-tasks to the Member States is not only laid down in EU Treaties, but in national constitutions as well. For example, the German Federal Constitutional Court’s Lisbon ruling restricts attributing supranational defence powers to the EU without a treaty amendment and a new German constitution. However, in its NextGenerationEU ruling, the FCC accepted temporary, supplementary (budgetary) measures under existing Treaties. This allowed the EU to borrow money to deal with the economic effects of the COVID-19 pandemic, in a framework with both supranational and intergovernmental elements. Although not allowing for adjustment in decision-making per se under the current Treaties, it did allow for additional EU-measures in a time of crisis. This suggests that, at least in German context, a limited, intergovernmental EU force is legally more feasible than a supranational structure, while even a more supranational model might be legally possible, as long as it is complementary to the Bundeswehr.
Democratic legitimacy also poses challenges. With intergovernmental decision-making, in theory, national parliaments oversee their governments’ decisions in the Council. However, in practice, it is hard for national parliaments to influence the decision-making of their governments. Strengthening (national) parliamentary involvement will therefore be essential for democratic accountability.
In a supranational model, to ensure legitimacy, the European Parliament would require expanded powers – similar to national parliament rights regarding national defence policy. Think of approving missions, overseeing defence budgets, or monitoring EU force deployments. In both, the supranational and intergovernmental variant, the decision-making model would have to account for the distinction mentioned before: out-of-area operations are judged differently in terms of democratic legitimacy than (collective) territorial defence.
Mandatory participation vs. voluntary “Coalition of the Willing”
Should all Member States be obligated to participate in an EU army? A mandatory structure ensures uniformity but faces political and constitutional hurdles, especially from neutral states like Ireland, Malta, and Austria.
A more pragmatic option is a “coalition of the willing”, where interested states collaborate on joint capabilities, similar to PESCO. This avoids lengthy treaty changes and allows ambitious states to advance cooperation. Also, it makes it easier to involve non-Member States as the UK and Norway. The 2022 Strategic Compass already steered in this direction, proposing to make use of the possibilities of Article 44 TEU when planning and deploying the EU RDC. However, in the end, collective defence is guaranteed only by credible deterrence and unity. Fragmentation through various “coalitions of the willing” therefore risks weakening collective defence.
To mitigate this, these coalitions should therefore at least operate within the EU’s institutional framework, simplifying legal coordination and still signalling unity. This also lowers barriers for other states to join later.
Conclusion
If the current geopolitical climate doesn’t prompt EU Member States to pursue deeper defence integration, what will? Recent emergency meetings of European leaders emphasized urgency but up till now yielded no groundbreaking steps for European security beyond Ukraine. It is also relevant to keep in mind that this debate is not just about autonomous capacities: military prowess directly reflects the diplomatic negotiation position, indispensable in a time where Europe is no longer able to rely on an accommodating American position in upcoming diplomatic talks.
For swift progress, a complementary force involving willing Member States under intergovernmental decision-making appears the most realistic path. However, the unanimity requirement in defence matters remains a major obstacle. Allowing qualified majority voting in certain cases could make EU defence more agile, provided that strong parliamentary oversight is ensured.
Whether Member States are willing to make these difficult choices remains an open (political) question, but it is ultimately the only question left, given the unfolding events.
The views expressed in this article are solely those of the authors and do not represent the position of the Dutch Ministry of Defence.
