This article analyses the dynamics of differentiated integration in EU defence. It contributes to assessing what Pernille Rieker (2021) terms ‘broader European capacity on the global stage’ involving both the EU’s defence structures and processes as well as those beyond the EU’s formal remit. The main argument in this article is that Permanent Structured Cooperation (PESCO) is bringing about two different and mutually complementary dynamics of integration: organizational field formation and segmentation. The preliminary practical result is a dual dynamic of growing standardization of the EU’s defence industries across all twenty-five PESCO Member States in defence project development and continued reliance on Western European defence industrial actors (including the UK after Brexit) in defence R&D and production. This means that while PESCO provides space for new joint defence projects across the participating Member States, the established structure and capacities of defence industries in the EU today set up conditions for what may be termed structural leadership by Western European defence industrial actors. Overall, this means that there is a particular – segmented – kind of differentiated integration in the field of EU defence industries in today’s EU (This article is an output of the EUFLEX project, which has been funded by the Research Council of Norway (project number 287131).).