Japan has been expanding its strategic focus towards the Asia-Pacific in foreign and security matters between 2005 and 2015. The new focus maritime security in the Pacific sidelines Japan’s traditional diplomacy in Asia and new defense cooperation has been implemented with Southeast Asian countries. However, policy implementation has been varying strongly under the DPJ administration, on the one hand, and the LDP on the other. Existing constructivist research emphasizes the role of cultural diplomacy in Japan’s new proactive policy towards the Pacific but provides little explanation of the continuous militarization of multilateral cooperation in Southeast Asia. Conversely, existing neorealist literature focusses on the important power shift presented by China’s rising military capabilities but says little about the underlying administrative process and motives of Japanese elite bureaucrats.

In order to fill this void, this paper offers a neoclassical realist analysis of Japanese elite-bureaucrats in the Ministry of Foreign Affairs (MOFA) and Ministry of Defense (MOD) and their impact on introducing strategic changes in Japan’s Asia-Pacific policy since 2005. This paper provides a process-tracing analysis of elite-bureaucrats and presents an explanation on how Japan’s new regional strategy was implemented as an attempt to counter Chinese assertiveness despite new uncertainties in U.S.-Japanese diplomacy under the DPJ government. This neoclassical realist study builds on personal interviews with elite-bureaucrats from the MOFA and MOD, as well as ranking staffers from the SDF in order to support the hypothesis of a new assertiveness among Japan’s Foreign Policy Executive.