The Mutual Defence Clause in the European Union: An Analysis of its Past, Present and Future

This Saar Blueprint examines the legal architecture of collective defence and mutual assistance in Europe. The security situation in Europe has changed dramatically in recent years. Not least due to Russia’s war against Ukraine since February 2022, calls for a (military) mutual assistance system among European Union Member States – one that is independent of NATO – have grown louder. Against this backdrop, this article examines and compares the conditions and legal consequences of the NATO collective defence clause and the mutual assistance clause under EU law, including in the context of Ukraine’s potential accession to the EU.