External differentiation as a strategy of system maintenance: EU enlargement towards the Western Balkans

Despite the stalling of enlargement countries’ accession to the EU, these countries have been recurrently involved in EU policies. There is, however, little knowledge about their participation in EU policies short of membership. This article conceptualises such participation as a manifestation of external differentiated cooperation. It offers a theoretical approach accounting for the unfolding of external differentiated cooperation in EU interactions with enlargement countries as a strategy of system maintenance. External differentiated cooperation, the article argues, serves as a strategy for the EU to address increased mutual dependences with enlargement countries triggered by crises-induced shocks to the EU system of regional integration. By examining EU-Western Balkans’ interactions from 2014 to 2023, the article shows that the EU and its relevant actors have resorted to external differentiated cooperation to ensure the functioning of the EU system of regional integration against the backdrop of member states’ reluctance towards EU enlargement.