This research conducts a study of the national security strategies introduced by the Koizumi administration (2001)(2002)(2003)(2004)(2005)(2006) and the second Abe administration (2012-). Based on the common themes of 'normalization', constitutional revision, in particular Article 9 and the right of collective self-defence, it examines through the theory of neoclassical realism how and why the national security initiatives of the two administrations are different in their extent of normalization of Japan. This dissertation has argued, using the approach of neoclassical realism, it was with the primary forces of international structural factors, together with the influence of domestic variables, that contributed to the enactment of the national security initiatives of Japan in different extent during the Koizumi and the second Abe administrations. Findings from the comparative study of the two administrations showed that the international environment surrounding Japan in the second Abe administration was more precarious with a heightened sense of threat perception than that of the Koizumi administration. The China threat and the North Korea threat was much