By Wang Xiaoyan and Feng Songjiang
During a recent inspection of an Air Self-Defense Force base in Fuchu, Tokyo, Japanese Defense Minister Shinjiro Koizumi publicly declared that space is an extremely important field involving the military and people's livelihood. Behind this statement lies the Japanese government's dangerous agenda of accelerating space militarization under the pretext of autonomous defense.
From plans to upgrade the Space Operations Group into the Space Operations Regiment, to efforts to reorganize the Air Self-Defense Force into the Air and Space Self-Defense Force, Japan is steadily advancing the build-up of its space combat capabilities. This series of moves to speed up the expansion of space militarization not only runs counter to Japan's pacifist constitution but also poses serious challenges to regional and global space security.
In 2018, the Japanese Ministry of Defense released the National Defense Program Guidelines, which explicitly stated that the Self-Defense Forces would maintain an Air Self-Defense Force unit that specializes in space domain missions, formally incorporating the development of space military capabilities into Japan's national defense strategy.
In March 2022, Japan's Ministry of Defense established the Space Operations Group by integrating two Space Operations Squadrons, with its command headquarters located at the Fuchu base. Its mission has shifted from research-oriented functions to preparations for real-combat operations. It is responsible not only for monitoring foreign satellites and space objects but also for leading the development and application of Space Situational Awareness (SSA) systems, making it the core command element of Japan's space military operations.
It is reported that the Space Operations Group will be upgraded to the Space Operations Regiment within fiscal year 2025, with plans to further elevate it to the Space Operations Command in 2026. The Space Operations Command will integrate capabilities across multiple domains, including space reconnaissance, counter-satellite operations, space-based navigation, and missile early warning, thereby forming an independent and comprehensive space combat system. Meanwhile, the establishment of the Air and Space Self-Defense Force signifies that its mission scope has formally expanded from traditional air defense to integrated air-and-space defense, fundamentally breaking the spatial constraints imposed by the "exclusively defense-oriented" principle on Japan's military operations.
Japan's push toward the militarization of outer space has been accompanied throughout the process by the parallel upgrading of equipment and technologies. The Space Technology Strategy released in 2024 repeatedly underscores such keywords as autonomy and indigenous development, clearly revealing Japan's intent to secure control over key technologies in order to provide fundamental support for the autonomy of its space strategy. At present, Japan already operates optical reconnaissance satellites such as the ALOS series and radar reconnaissance satellites, including the StriX, enabling high-precision imaging of ground targets and all-weather surveillance capabilities. In addition, Japan is advancing the development of the Quasi-Zenith Satellite System (QZSS), with plans to improve positioning accuracy over surrounding areas by increasing the number of satellites. It could provide independent space-based guidance support for long-range missiles, combat aircraft and other platforms, reduce reliance on the US GPS, and pave the way for independent military operations.
The rapid acceleration of Japan's militarization of outer space is driven by a combination of external and internal forces. Externally, strategic support from the US provides crucial security backing and access to advanced technological resources. Internally, Japan seeks to disguise its military buildup through tactics such as the civilian-to-military transfer of technologies, thereby evading scrutiny from the international community and expediting armament efforts.
At the same time, Japan has laid the groundwork for space militarization through technological camouflage and conceptual obfuscation. For a long time, Japan has accumulated a military technological foundation under the cover of so-called civil space activities.
Its push toward the militarization of outer space not only runs counter to the core principles of the Outer Space Treaty and Japan's pacifist constitution, but also poses multiple risks to regional security and stability.
From the perspective of regional security, Japan's space militarization will disrupt the existing strategic balance and could trigger an arms race in outer space. Moves such as accelerating the development of low-Earth-orbit satellite constellations, researching satellite interference technologies, and conducting regularized joint orbital warfare exercises with the US will inevitably compel neighboring countries to strengthen their countermeasures. Even more dangerous is Japan's reliance on the US-Japan alliance to embed its space capabilities into the US military operational system, accelerating the spillover of regional conflicts into outer space and significantly increasing the risks of miscalculation and chain reactions.
From the perspective of global space governance, Japan's militarization of outer space runs counter to the international consensus on the peaceful use of outer space. Since the signing of the Outer Space Treaty in 1967, principles such as the prohibition of weapon deployment in outer space and the peaceful use of outer space have become widely accepted norms of the international community. By defining outer space as an operational domain and advancing the establishment of the Space Operations Command, Japan is, in essence, weaponizing and turning outer space into a battlefield, which is in clear violation of the core spirit of the Outer Space Treaty. Japan is also attempting to construct a so-called space security alliance, joining forces with NATO and others to advance military cooperation in outer space. Such bloc-based and confrontational practices would fragment the global space governance system, undermine international cooperation in areas such as space debris mitigation and satellite frequency coordination, and inflict serious damage on the sustainable use of outer space resources worldwide.
(The authors are from the Space Security Research Center, PLA Space Engineering University.)