This study examines the evolution of Nordic security cooperation from the perspective of minilateralism and analyzes the formation of the Nordic Defense Cooperation (NORDEFCO). Minilateralism in a small group of countries can respond more effectively to uncertainty in international affairs compared to the existing large-scale multilateral system. Previous studies have analyzed the tradition of Nordic defense cooperation and its concept of a security community from the lens of constructivism. However, this study argues that Nordic countries have formed new partnerships to cope with the recent common external threats. The initial goal of the NORDEFCO was to promote substantial military capabilities along with security cooperation between member countries. Currently, the aim of strengthening military capabilities through inter-operability has not been fully achieved, but progress has been made to establish joint military training, such as Arctic Challenge Exercise, and regular dialogue channels on security issues. NORDEFCO has also strengthened its strategic position by supplementing, rather than replacing, the existing NATO and the EU's CSDP. NORDEFCO shows that minilateralism can be promoted without conflicting with the multilateral cooperation system. It provides useful implications to other parts of the world, including East Asia, in terms of low-level security cooperation and dialogue process that has a practical value as an early step toward institutionalized regional security architecture.