Japan, Space Security, and Defense Buildup: Perspectives from Recent Strategies

• Commentary Asia
  by Nanae Baldauff
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Japan has come a long way since it changed in 2008 its space orientation, from near-total civilian focus to one that is balanced with national strategic objectives. The country is situated in a harsh environment, surrounded by three nuclear states, which have been determinedly strengthening their national powers. Japan's three strategic documents issued in December 2022 - the National Security Strategy, National Defense Strategy, and National Defense Buildup - address its security and defense objectives, and the means to achieve them in the defense of its national interest.

Space is at the heart of Japan's fundamental reinforcement of its defence capabilities. Among the seven priority areas listed in the National Defense Strategy, the majority of them cannot be achieved without space-based capabilities. The stand-off defence systems - long-range, multi-domain offensive and defensive systems - can only be possible with a robust satellite constellation for long-range target detection and tracking. With a budget of ¥280 billion (US$ 2 billion), Japan is aiming to develop an optical and SAR satellite constellation for the purpose of intelligence, surveillance, reconnaissance and targeting (ISRT), together with commercial companies. The project aims to provide Japan with continuous real-time situational awareness over the vast area surrounding its territory, extending more than 3000km in all directions. Likewise, Japan's integrated air and missile defense capabilities must have a robust system to enable unified and optimized operation of various sensors and shooters through networks. Space-based capabilities will be an obvious part of this reinforcement.

Another key priority, among the seven listed, is related to unmanned defense capabilities, not only conceived as land-based, aerial and underwater autonomous vehicles, but also including non-terrestrial networks, such as high-altitude platform stations (HAPS), drones, and orbital assets. As connecting these different platforms across domains for detection and targeting will be vital, space-based assets will be a crucial component of the entire network.

The fourth priority concerns cross-domain operation capabilities. There is no time to waste in integrating capabilities across all domains - space, cyber, electromagnetic spectrum, land, sea, and airspace - to generate synergy and amplify the overall strength, thereby ensuring Japan's national defense. To achieve this, space-based assets such as intelligence collection, communication, geolocation and precision, will be indispensable. In line with this, Japan is establishing a Space Domain Awareness (SDA) system, and its first SDA satellite is on track to launch within the fiscal year 2026. The fifth area is Command and Control (C2), backed up by fundamentally strengthened intelligence. The objective is to support rapid decision-making for defense and other operations such as disaster management. Without space-based intelligence, none of the priority areas described above can be achieved.

Deteriorating security environment in space

Space is vital and indispensable to all aspects of modern way of life. Satellites provide services such as communications, earth observation, positioning navigation and timing (PNT), making up the foundation of socioeconomic activities. Their centrality makes them a potential prime target to reduce countries' ability to conduct military operations, as space is becoming a crucial operational domain. One of the ways to cause damage to a satellite or destroy is through ground-based anti-satellite (ASAT) missiles. The most recent example was Russia's direct-ascent anti-satellite missile test in 2021, which generated more than 1,500 pieces of trackable orbital debris. Laser systems are another counterspace application, which can be either space-based or ground-based. Within the electronic warfare domain, jamming or spoofing global navigation satellite systems such as GPS has become common since Russia's invasion in Ukraine in 2022. Finally, there are satellites that conduct suspicious maneuvers, such as rendezvousing with other space objects. It is also recalled that the war in Ukraine started with Russia's cyberattack on Viasat communication network which successfully disrupted internet services in Ukraine.

Japan's efforts in space should be understood within this broader context of an ever-severe security environment in general, but particularly in and from space. On 28 July 2025, Japan's Ministry of Defense published its Space Domain Defense Guidelines. As the first of its kind, the document sets the strategic direction for strengthening defense capabilities in the space domain. As Japan is also in the midst of institutional reform to become an effective warfighting entity, this document systematically organizes how the country intends to use and defend its space capabilities. Four approaches are listed: rapid and accurate battlespace awareness; satellite communication which provides the operational foundation for warfighting; mission assurance by building capabilities in space domain awareness, resilience of the entire space system; and disruption of adversary's command and control and intelligence capabilities. As many of these capabilities are still in development, the value of this document lies in the systematic organization of measures a protect Japan's space assets. This document signals Japan's intent to engage its commercial space sector, which possesses the technologies necessary to achieve national defense objectives.

Equally important is the publication of its Next-Generation Information and Communications Strategy, which was released by the Ministry of Defense simultaneously with the above-mentioned guidelines. As platforms - both manned and unmanned - become ever smaller, agile, fluid, proliferated, and expendable, they must be linked together to be effective on any battlefield. In order for Japan to intervene in the seven priority areas mentioned above, utilizing next-generation information and communication technology (ICT) is imperative. As Japan considers ICT infrastructure as critical for its security and the functioning of its society (for transport, energy, finance, natural resources management and disaster management for example), this strategy effectively supports Japan's entire economic security efforts, underpinned by autonomy and indispensability. The fact that these two documents were released together illustrates a clear shift in Japan's defense posture, highlighting how the Ministry of Defense intends to turn from an isolated end-user into an active participant and stakeholder within the security and socio-economic fabric of the nation.

The strategy puts forth three ways to achieve an autonomous and indispensable architecture: establishing decision-making superiority; building a multi-domain effect web; and strengthening resilience. Japan aims to establish a new defense information communications architecture - a name which is yet to be given - which is made up with four layers: the first is the sensor shooter layer that connects various sensors and platforms - both very expensive and inexpensive - from all domains to enable sustainable warfighting; the second is the network and infrastructure layer that allows the rapid flow of huge data through multiple networks minimizing latency; the third is the data layer that organizes and optimizes the data using AI and edge computing; and the fourth is the service layer that transforms actionable data for different tactical applications. Japan is looking to build a data-centric, integrated-information and communication architecture through hybrid and cloud-based infrastructure to adapt to an ever-changing battlefield.

What's missing in Japan's space endeavours

Still, ensuring space security is only one of the four space goals Japan aims to achieve. The Fifth Basic Space Policy - approved by the Cabinet Office in June 2023 - states that Japan aims to achieve: security in and from space, national resilience and solving global-scale issues and innovation, creation of new knowledge and industries through space science and exploration, and 4) strengthening the national industrial base to support space activities. Japan aims to scale up its domestic space market from the current 4 trillion yen to 8 trillion yen (US$ 27.5 billion to US$ 55 billion) by 2030. Japan is counted as one of the six autonomous space actors, covering the most important technological areas: launch to the most useful orbits; secure SATCOM; PNT; Earth observation/intelligence, surveillance, and reconnaissance (ISR) industries; and LEO and GEO launch capabilities.

However, Japan's space sector is still missing a number of elements that have proved relevant in the strategy of other space powers. The first missing element is branding. The US names its multi-layer defense system as the Golden Dome. Israel refers to its mobile, short-range air defense system as the Iron Dome. Japan's equivalent, however, remains as "the integrated air and missile defense capabilities". The above-mentioned new defense information communications architecture remains nameless. While the technical details may be sound and convincing, the absence of branding risks alienating the Japanese public from the very systems designed to protect them.

Furthermore, as far as implementation is concerned, national "spacepower" is only part of the overall power of a state. In other words, it is the totality of a nation's ability to exploit the space domain in pursuit of prosperity and security. A case in point relates to launch capability. Japan targets to have 30 rocket launches per year by 2030. In an era of SpaceX that includes the Falcon 9, Falcon Heavy, and the Starship system offering a range of payload capacities and reusability, Japan's target lacks ambition to say the least. And finally, to achieve Japan's efforts in strengthening defense capabilities in space, Tokyo needs a dedicated operational and doctorial concepts. Why does Japan's Air Self Defense Force (JASDF) - which will be renamed as the Japan Air and Space Self Defense Force in 2027 - exist? Who are the personnel within this organization, and how do they use its power to achieve Japan's defense objectives? Such concepts are necessary to establish space superiority and help guide Japan's evolution in space security and how JASDF would serve in those endeavours.