Enlargement as a Strategic Necessity: How Russia’s War of Aggression Against Ukraine Reshaped EU Policy Priorities

Russia's full-scale invasion of Ukraine in 2022 has triggered a fundamental rethinking of the European Union’s enlargement policy, transforming it from a primarily normative instrument of foreign policy into a core strategic and geopolitical imperative. This paper examines how the war in Ukraine has redefined the rationale and urgency behind EU enlargement, situating it within a broader shift in the Union’s security priorities. Previously centered on economic interests, enlargement is now increasingly perceived as essential tool to reinforce the EU’s geopolitical presence, military preparedness, and resilience against authoritarian threats in its immediate neighbourhood. Multiple studies argue that this shift reflects a paradigmatic evolution in EU policy, whereby enlargement is no longer a supplementary objective, but a central mechanism for securing a stronger, more integrated Europe capable of collective defence and democratic consolidation. At the same time, this reconfiguration faces significant internal challenges, notably the resistance from certain Member States — such as Hungary and Slovakia, for instance, — whose illiberal tendencies and obstructionist positions raise concerns about institutional cohesion and democratic conditionality. Based on recent policy developments, official EU communications, and comparative analysis of member state positions, the paper aims to explore the emerging model of strategic enlargement and its implications for future EU governance. It proposes a comprehensive approach combining differentiated integration, targeted treaty reform, and enhanced political conditionality as a viable pathway for implementation. Ultimately, the paper contributes to the scholarly debate on EU enlargement by framing it not only as a policy of inclusion, but as a structural necessity for the Union’s survival and credibility in a volatile geopolitical landscape. Building upon theoretical frameworks within the study of European integration (i.e. post-functionalism, liberal intergovernmentalism, and strategic autonomy theory), the paper examines a transformed enlargement model grounded in: 1. geopolitical conditionality; 2. differentiated integration; 3. institutional adaptation. The paper concludes that if enlargement is to serve its newly assumed role as a geopolitical necessity, the EU must overcome internal fragmentation through innovation in governance structures and a reassertion of core democratic values. As failure to do so would not only undermine the EU’s credibility among candidate countries, such as Ukraine and Moldova, but would also embolden external authoritarian actors seeking to exploit European vulnerabilities. By reconceptualising enlargement within the current geopolitical context, the paper contributes both to ongoing academic and policy debates on the future of the EU as a global actor, and the long-term sustainability of its integration model.