This article has mapped and analyzed internationaldefence cooperation with an emphasis on developments in NATO. In the mapping ofthe processes of defence cooperation initiatives in NATO after the Cold War and9/11, we concluded that there has been a steady stream of capabilitycatalogues, coordination measures and creation of joint ventures. In theanalysis we noted the different types of defence cooperation initiatives(sharing of capabilities, pooling of capabilities, role- and task sharing,co-development, and pooling of acquisitions), the character of the process(sequential and repetitive), and the dynamic and conditions (trade off dynamicsinfluenced by perceived gains, degree of solidarity, strategic similarities,degree of common understanding of political investment, and geographicproximity). The final part of the text elaborated on the potential consequencesof international defence cooperation; in this part we concluded that the threecategories, that might well mirror the future of the transatlantic securityarchitecture, are minimal defence cooperation, flexible defence cooperation orregional defence integration.