Borders and Liberal Political Communities: The EU at the Test of Time

The contemporary global political landscape is defined by the acute tension between the hardening of borders' normative meaning and persistent elements of cosmopolitan self-identification. The European Union, historically viewed as the primary laboratory of the Liberal International Order (LIO) built on the principle of softening borders, stands as the natural epicenter of these multidirectional dynamics. This paper argues that the EU’s approach to borders has undergone a fundamental transition from a selective policy choice to an institutionalized, multidimensional framework for strategic defense, a conscious political choice that accelerates the shift toward Defensive Liberalism, profoundly altering the EU's foundational identity. To substantiate this transformation, we perform a comparative analysis of the strategic priorities set by the European Commission in 2019 against those outlined in the 2025 Work Programme, the 2024-2029 Strategic Agenda, and the pivotal 2025 Enlargement Package. Our evidence confirms a decisive structural re-bordering that is strategically tied to the future composition of the Union. The Institutional Border is now the central domain of the EU’s defensive strategy. While the 2025 Enlargement Package notes accelerated progress for frontrunners, particularly the political impetus behind Ukraine's accession, it simultaneously mandates strict internal EU reforms and demanding safeguards against backsliding. This process transforms the Geopolitical Border: the acceleration towards Ukraine elevates Russia to the primary antagonistic line of demarcation, turning the EU's Eastern border into a military and ideological defence line that explicitly replaces the LIO's logic of convergence with one of containment. This tension—accelerating the expansion of the territory while simultaneously and decisively tightening the normative conditions for entry and internal adherence—underscores a deliberate effort to consolidate the internal political community. By deploying its borders, both external and institutional, as rigid lines of distinction, the EU’s trajectory toward a Defensive Liberalism confirms the conscious sacrifice of the LIO's foundational porosity for the sake of security, cohesion, and self-protection in the face of heightened geopolitical competition.