Abstract
This article examines several theoretical ideas on security regime applicable to Northeast Asia. Different from realists or idealists, two schools of international relations theory, neo-liberal institutionalists have seen that anarchy and mixed interests occasionally cause states to suffer the opportunity costs of not achieving an outcome that is more mutually beneficial. In this context, the concept of co-operative security regime has important connotations for the concept of neo-liberal institutionalism. Based on the research outcome, the co-operative security concept appears to be the most applicable to Northeast Asia in that the idea is among the more widely used terms, complementing more traditional views, acknowledges a more inclusive definition of security, and challenges to security, encompassing, but moving beyond, the traditional notion of military threat and response. Beside of this reason, there are four more logics validating the application of the co-operative security regime notion to Northeast Asia.