Japan’s space security commands attention as the country shifts toward internationalism in a world returned to great power competition. Using the framing from neoclassical realism, this article discusses the ways in which Japan has adjusted both its internal portfolio and its external postures to balance against perceived threats in outer space. While neoclassical realism is foundational for understanding what motivates, empowers, and constrains states in the space domain, the article also layers in the importance of international law to the conduct of statecraft within it. Doing so gives us a more holistic understanding of the material, legal, and normative evolution of Japan’s winding space trajectories. Although Japan’s Basic Space Law of 2008 is seen as a watershed event for legal and policy purposes, the law merely caught up with the extraordinary quality and range of Japan’s long-evolving dual-use space technologies. It is these autonomous foundations that empower Japan to pursue three distinct strategies in its interest—counterspace capabilities, organizational changes, and space diplomacy—with implications for both rivals and allies in a changed world order.
