The Russia’s war against Ukraine and the United States’ gradual disengagement from European security have prompted the European Union (EU) and its Member States to reassess their defence posture, with renewed attention to the Western Balkans. Once sidelined due to stalled enlargement efforts, the region has re-emerged as a strategic priority. The dominant narrative states that EU’s defence cooperation is increasingly aligning the Western Balkan’s foreign policies with EU objectives, potentially reinvigorating the enlargement process. However, this policy paper argues that this geopolitical turn has overlooked risks: the erosion of the EU’s modernisation approach to build peace in the Western Balkans, regional fragmentation due to uncoordinated defence initiatives, and the potential escalation of conflict amid fragile power dynamics. By analysing these multi-level risks, this policy paper questions the assumption that defence cooperation naturally supports EU enlargement and explores the tension between the logics of modernisation and geopolitics in EU foreign policy. Finally, it puts forward three policy recommendations: re-centre cooperation around peace and democracy; embed a regional lens in defence cooperation; and ensure that defence alignments do not fuel fears or distrusts among the Balkan countries. The analysis is structured across three sections: the EU’s strategic shift in the Western Balkans, its defence engagements, and the unintended consequences of this approach.