Why the New Defence Boom in the EU Won’t Lead to a "European Defence Union"

Despite a surge in EU defence spending and the launch of the ambitious ReArm Europe package, this report argues that a true European Defence Union remains out of reach. Legal, political, and institutional constraints continue to limit the EU’s ability to act as a unified military power. Instead, the EU’s growing role in defence is rooted in its strengths as a market and regulatory actor. By leveraging its internal market, financial instruments and industrial policy, the EU is positioning itself as a key enabler of defence capacity — not a military alliance. Rather than competing with NATO, the EU is carving out a complementary role, focused on industrial coordination, procurement and mobility. This report explores the implications of this evolving role and outlines how the EU can best support European security without overreaching its institutional limits.