China’s Military Modernization in Space and Cyber and the Implications for the U.S.–Japan Alliance

China’s Military Modernization in Space and Cyber and the Implications for the U.S.–Japan Alliance

by Yuka Koshino
January 6, 2022

This essay discusses why China’s rapid development of space and cyber capabilities poses security threats for Japan, how Japan is trying to respond, and what Japan and the U.S. could do to address these new challenges.



China’s rapid development of military and technology capabilities in new domains, especially in the realms of space and cyber, poses serious security concerns for the U.S.-Japan alliance. First, the development and deployment of offensive capabilities in these domains could give China an asymmetrical advantage to challenge existing deterrence created by the alliance in the Indo-Pacific region. Second, China’s Military-Civil Fusion strategy and the dual-use nature of these domains expand the security concerns into the civilian and commercial realms. Third, Japan’s unique constitutional, legal, and political constraints challenge the country to effectively respond to such new security requirements in diverse scenarios from peacetime to conflict. Beijing’s increasing use of cyber tools during peacetime to prepare for the future annexation of Taiwan further underscores the need for the U.S. and Japan to coordinate on responses and define their roles and missions under the alliance in a wide range of scenarios.

  • On the strategic level, the U.S. and Japan should coordinate a whole-of-government approach beyond their existing defense-focused cooperation in order to deal with the multidimensional challenges posed by China’s pursuit of “information dominance” beyond the military realm.
  • On the military level, the U.S. and Japan should enhance the credibility of deterrence against cyberattacks through greater coordination in high-level dialogues. Linking Japan with like-minded U.S. allies beyond the region could further strengthen Japan’s operational capabilities.
  • On the economic-security level, the U.S. and Japan should encourage public-private cooperation in order to facilitate real-time information sharing on trends in cyberdefense and to maintain technology superiority in advanced dual-use technologies in the new domains.

Yuka Koshino is a Research Fellow with the International Institute for Strategic Studies (IISS).