The changing of geopolitical environment in Northeast Asia after the Cold War illustrates some
fundamental shift in Japan’s security environment. The post-Cold War era provide a new set of
challenges and difficulties that must be diligently comprehend not only by Japanese policy maker but
also her military echelon as well. With the receding of Soviet Union threat from the north comes a
new and emerging volatile situation from her immediate neighbors; People’s Republic of China and
Democratic Republic of Korea. Aside from this, threats from Japan domestic security also did not
demonstrate any indication of declination. This article explores each international actor that can be
considered as security predicament to Japan and why each actor behaves in an aggressive manner
towards Japan. By analyzing issues that occur both domestic and beyond her border, the author show
how past threats that emerged will eventually be replace by a new and more volatile situations –
instances where PRC challenging Japan sovereignty over Senkaku and DPRK nuclear and ballistic
missile test. Variety of methodology tools has been used to provide an adequate data analysis to
interpret every states action in Northeast Asia, ranging from the using of primary and secondary
sources that seek to contribute to the argument of this article.