Conflict and cooperation are constants in the discipline of international relations. In the case of the Republic of Korea’s (ROK) and Japan’s bilateral military relations, the overwhelming interest in what drives conflict has tended to overshadow any analysis of diplomatic cooperation. In fact, many have cited the lingering effects of the Cold War to be one of the key driving forces behind the dynamics surrounding the Korean peninsula,1 what Victor Cha calls, ‘a stickiness of Cold War thinking’2 that has perpetuated a discourse mired in the vocabulary of realism. Subsequently, realism has served as the default explanation for the rationale of interaction within the Northeast Asia region, with no rigorous empirical testing of whether those ‘truisms’ are indeed grounded in facts. Hence, the underlying motivation behind this paper started with questioning whether security, and thus, accordant cooperation in Northeast Asia was really driven by realism. Specifically, how much explanatory power do the various theoretical discourses have in accounting for the instances of bilateral military cooperation between Seoul and Tokyo?