Abstract:  Starting from the mid-2010s, the European Union (EU) and, in particular, its supranational executive, the European Commission, started to play a role in defence industrial policy that is completely unprecedented. The Commission now supervises a whole array of financial instruments and can use them to nudge member states to develop certain sectors and capabilities. Combining insights from neo-functionalist European integration theory and neo-realist international relations, this article devises the concept of “isomorphic spillover.” I argue that competitive, mimetic, and normative socialization with sovereign states creates opportunities for integrationist entrepreneurs to make the EU more state-like, expanding its jurisdiction in the process. The security logics of the “geo-tech world” are thus transforming European integration. That said, isomorphic spillover has limits. The EU’s efforts to resemble states are constrained by the fact that it pursues its aims via regulatory powers rather than centralized administrative capacity. While defence industrial policy is an extreme case that illustrates the EU’s challenge in particularly stark terms, the logic of the isomorphic spillover has the potential to be applied across all areas of industrial policy.

Keywords:  defence integration; European Union; industrial policy; neofunctionalism; spillover

Published:   14 January 2026

Issue:   Vol 14 (2026): Doing Industrial Policy in a Geotech World: Challenges and Opportunities (In Progress)