This article situates recent initiatives to deepen security and defence cooperation in the European Union in the historical perspective. It proposes a model of constitutive relationship between the process of change in a security community and the formation of a transnational defence industry community of practice which yields positive feedback (‘productive returns’) to the security community as a broader assemblage within which it was constituted. This model is applied to the paradigmatic case of European security community that formed after the World War II (WWII). The analysis shows that the key driver for defence integration traced by means of social network analysis (SNA) in this case was economic rather than political, and for an extended period of time it developed without formal institutions. The productive return of the ‘defence industry machine’ as a distinct community of practice that was constituted through the integration process consisted in the sense of deeper belonging and a shared sense of working well together in a traditionally highly nationalised defence milieu.