Discussions about ethnic minorities as a threat to national security are recently being extensively escalated. (Zainichi) Koreans in Japan is the largest ethnic minority in the country. Pro-North Korea Zainichi Koreans have already been presented sporadically in this context. Nevertheless, bearing in mind their troubled identity, a more thorough discussion is required, taking in account all of the Koreans in Japan. This presentation provides a theoretical approach implementing the framework of threats to national security by Rex Brynen for an upcoming empirical research.