A great many studies exist that attempt to explain why North Korea (NK) continues to survive. Some consider NK's possession of nuclear weapons as one of the primary factors; others argue that the balance of conventional forces between NK and the United States (US) has worked as a mutual deterrence. These arguments, however, cannot explain the stalemate over the past 70 years, and it is known that the balance of power does not reduce the likelihood of war.In addition to these traditional arguments, another factor that should be noted in considering the survival of NK is the recent economic situation of the state. The economy in NK remains weak, while an emerging (black) market economy is changing not only its economic system, but also its governance system. Along with weakening state control, market activities have been revitalized, which provides individuals with incentives to work in their own self-interests. The separation of the state-run economy and the market economy forces NK to raise funds for reigning by itself. In addition to this internal change, there exists some exogenous stimulation to its economy. China, Russia, India, and other countries have trade relations with NK under United Nations' sanctions. The total amount of trade reached $6.5B in 2016, which may help NK survive.Hirose and Kurizaki (2019) clarify the logic of the survival of NK by focusing on its ethnic homogeneity. They present a two-level game model that considers the interactions between domestic and international conflicts, in which not only the relationship between NK and the US, but also that between NK and opposition groups in the state are considered. Based on this model, they conclude that the ethic homogeneity of NK led to the small military contribution of its opposition groups to interstate war, which resulted in the survival of NK. The model in Hirose and Kurizaki is significant in clarifying the relationship between ethnic composition and the likelihood of intrastate or interstate wars. The model can consider possible interactions between domestic and international conflicts, which imply what strategy should be chosen by both states. †Correspondence: Yuji Sato,