Citizen Support for a European Defense Union: An International Conjoint Experiment on Security Cooperation in Europe

Abstract Even in the face of rising security threats, European regional security cooperation is fraught. The issue strikes at the heart of national sovereignty that citizens and governments can be jealous to preserve. Political support for European security integration is arguably sensitive not only to financial and sovereignty costs, but also to specific design choices—its scope and level of military commitments, its governance and sources of financing. To explore these issues, we carried out a conjoint experiment in five Western European countries (France, Germany, Italy, Netherlands, Spain) in November 2022 focused on public support for alternative designs of European defense union. The results show that these Western European publics are most supportive of policy packages requiring EU-level governance, joint procurement of military equipment, and repurposing of existing national expenditure as the preferred form of financing. Citizens in different Western European countries have generally aligned preferences regarding such security cooperation. The results suggest that European citizens support creating joint institutions and policies that substantially pool sovereignty even in the security realm—provided such pooling stays within a range of particular policy designs.