Repositioning the U.S.-Japan Alliance for Space

This commentary is part of the Exploring New Horizons: Japan’s Defense Priorities project, a CSIS Japan Chair initiative featuring analysis by leading Japanese and American scholars examining the implications of Japan’s new national security and defense strategies and opportunities for bilateral cooperation.

A dominant narrative is that the U.S.-Japan Alliance is a cornerstone of prosperity and stability in a world returned to great power competition. This narrative is in play in the unfolding bipolar contest between the United States and China worldwide and permeates the international relations of Asia and beyond. It now also extends to space, which intersects with virtually all existing and emerging technology frontiers. The U.S.-Japan alliance is the first and currently the only alliance that extends a formal military pact to outer space. Leadership in both countries has spoken about the importance of protecting against harmful and malicious actions against space assets, and even about gaining superiority in the space domain.

This commentary assesses the prospects for the U.S.-Japan alliance in, through, and at the nexus of the contemporary space domain. It surveys the threats the two allies face, their collaborative responses to date, and, looking ahead, the interconnected technology frontiers that will require preemptive and sustained diplomacy to reposition their allied interests in the final frontier. Three elements are critical to that mission: capabilities, clarifications, and communications.

Shared Understanding of Threats in Space

The space domain is one of the critical technology frontiers in a changed international order. Japan’s foremost ally, the United States, has marked geopolitics with a return to great power competition and has also marked space as a warfighting domain. That broader context suffuses realities in the space domain in which satellites form a critical digital infrastructure for all spacefaring powers. Satellites invisibly empower economic, environmental, and social realities and link military defense with the nuclear, cyber, artificial intelligence, and quantum frontiers. Such space-based infrastructure is expanding in unprecedented ways, with small satellites and mega constellations led by commercial innovators in the United States as well as Japan. 

It is threats to the expanding orbital infrastructure that are of more immediate concern to the United States and its allies. Setting aside natural hazards, this infrastructure is threatened by accidents. Satellites can simply collide, and this is even more likely if the proposed 100,000 or more satellites bound for low Earth orbit (LEO) materialize in the years ahead. In 2009, a functioning U.S. Iridium satellite collided with a defunct Russian satellite, spewing debris. Older satellites can also break apart, as a 20-year-old U.S. Air Force weather satellite did in 2016. All of these accidents generate orbital debris, and orbital debris represents a nondiscriminatory threat to all space operations. It travels much faster than a speeding bullet in LEO and can be lethal for humans and machines that get in its orbital pathway.

The bigger challenge is that threats to space assets increasingly result from deliberate actions—kinetic, non-kinetic, electronic, and cyber—all of which are amplified in the return to great power competition. No orbit is safe or secure. Among the most-high profile actions is the Chinese anti-satellite (ASAT) test in 2007, in which China used a direct-ascent missile to take out one of its own satellites. That demonstration created huge amounts of orbital debris that will long be circling and endangering outer space activities given their lethal speed. But China is not alone. Other countries have also followed suit in terms of demonstrating their direct-ascent ASAT capabilities with or without generating orbital debris, most notably the United States in 2008, India in 2019, and Russia in 2021. The presence of ballistic missile defense systems, and especially interceptors, that can be modified for ASAT capability to target satellites in their determined and knowable paths means that Japan is in the mix as well.

The threats also extend to geosynchronous orbit, where preemptive strikes against U.S. nuclear command and control satellites for communications and early warning cannot be ruled out. China reportedly tested a high-altitude rocket in 2013 that could target satellites in deep space. An additional concern stems from rendezvous and proximity operations (RPOs), in which two objects are intentionally brought together or kept at a planned distance for a specific time and purpose. The United States, Russia, and China have all reportedly either carried out or have the capabilities for RPOs in geosynchronous orbit. This can be done for understandable reasons, such as servicing older and malfunctioning satellites in all orbits near and far from Earth. Complicating matters, however, are the ambiguities of dual-use space technologies. The very same space-servicing technologies can also be used to inspect, image, disable, degrade, damage, or destroy rival satellites and spacecraft. Japan’s RPO capabilities should not be underestimated on these fronts. Japan is an early tester in this area and has been developing and testing such potential counterspace technologies in public since at least 1997. Japan’s Hayabusa spacecraft has traveled billions of kilometers to land on, image, take off, and fire projectiles into asteroids in the name of scientific exploration. These Hayabusa missions give us some sense of what Japan can see, do, and endure over huge distances with its RPO capabilities.

These trends suggest that space has moved well beyond its characterization as only contested, congested, and competitive. Today, there is open talk about weaponization and arms races in space, and the possibility of conflict in and through space. Stakeholders cannot—and frankly should not—take it for granted any longer that they can get to, use, and move about in space free from threats of disruption.

Present Indicators of Alignment

Both the United States and Japan are also responding to the space threats that are deeply rooted in geopolitical considerations. The U.S.-Japan alliance is central to that mission, and it has extended to outer space with an eye to balancing China and Russia. The alliance has also been fortified by the increasingly negative and pessimistic prospects for peace in the international relations of Asia. Aside from global and regional security concerns, there are at least four indicators that suggest that the United States can count on Japan’s continued alignment with its postures and policies in the space domain.

First, in addition to its advanced space capabilities, Japan is now institutionally geared up to devise homegrown measures for countering space threats. Japan has steadily synchronized its legal and policy building blocks to bring that outcome about. In 2008, a Basic Space Law opened the door for Japan to engage in the military uses of space in line with international interpretations. In 2012, the Japan Aerospace Exploration Agency (JAXA)’s foundational law was also modified to allow it to engage in military space activities. Since JAXA is and will remain the powerhouse for space research and development, this legal change is significant because it means JAXA can engage in national security space technology projects, such as with the Ministry of Defense, and this is considered a top goal by JAXA’s leadership today. The Ministry of Defense is also engaging with Keidanren, Japan’s business federation, to promote commercial defense equipment and technologies, made possible with the 2014 easing of the arms export ban. With changes in its legal frameworks, as well as Article V protections of the U.S.-Japan security treaty extended to space in January 2023, Japan is poised to move into counterspace weapons and to rethink its disruptive and offensive actions (most likely non-kinetic) in, through, and at the nexus of space. 

Second, Japan is one of the world’s preeminent space powers and intends to stay that way. It has longstanding and culturally deep-rooted ideas about how technology makes countries wealthy, strong, and secure in the long run. Japan seeks to leverage its space industrial base by creating technology platforms to counter space threats through the U.S.-Japan alliance. The two allies can build on a long history of technical and technological cooperation, including over ballistic missile defense since 2003, which remains an important element for space security purposes. Both countries are most interested today in building out the technology platforms for space domain awareness (SDA), which would allow them to counter natural, accidental, and deliberate threats against their space assets, as well as the security they underwrite globally and regionally. The basic idea is to build a better map of what is going on in space. Japan’s QZSS satellite positioning, navigation, and timing (PNT) system, for example, will complement the U.S. GPS system, and the United States has delivered its military sensors to be hosted on QZSS satellites. The joint effort is aimed at expanding the orbital view of the U.S. Space Surveillance Network by providing observation data on satellites and space debris in a region now not sufficiently covered by U.S. radar and telescopes.

Third, Japan set up its own dedicated space force in 2020, called the Space Operations Squadron (SOS), part of the Japan Air Self-Defense Force. In collaboration with other players, such as JAXA, and some increased budgets, the SOS is poised to play a symbolic public role in advancing Japan’s technological basis for a space monitoring system. This will reinforce the allied emphasis on SDA as well. The SOS aims to help develop Japan’s technical and human expertise to operate in space, and this will help to bring the two allies together as well in terms of doctrines, strategies, and operations. Japan has been engaged in the U.S. Shriever space wargames since 2018, and Japan is also a part of the new Multinational Space Collaboration Office at Vandenberg Air Force Base, a new unit for U.S. allies to align policies and tactics, techniques, and procedures. A Japanese liaison officer is also part of U.S. Space Command, engaging in space operations. The SOS is also likely to be central for space defense cooperation with the United States in the context of the alliance, particularly on expanding SDA and space situational awareness collaboration and devising ways to extend both to other members of the Quad. Japan has also set up a second space operations unit, to deal specifically with monitoring threats via electromagnetic waves to its satellites.

Fourth, Japan has signed up to the U.S.-led lunar projects, principally under the umbrella of the NASA Artemis program to return humans to the moon. Japan is building on a long track record of civil cooperation with NASA on the International Space Station (ISS) that, today, also morphs into commercial space realities. Japan signed up as a founding member of the Artemis Accords in October 2020, which are guidelines for civil exploration and activities on the Moon, Mars, comets, and asteroids. In 2021, Japan formalized an agreement on Gateway, an outpost orbiting the Moon to facilitate long-term human presence on the Moon. Japan has also participated in missions to the ISS on SpaceX rockets, and Japan’s leadership aims for the country to become the second to land an astronaut on the Moon. It is naive to see the Artemis alignment as just civilian or commercial. The U.S. Space Force has signed a memorandum of understanding with NASA to “expand” in this area, and the Defense Advanced Research Projects Agency has initiated a program focused on manufacturing large-scale orbital and lunar structures in space. This suggests that there are clear and present U.S. Department of Defense interests in activities as well as bases or outposts on lunar and other celestial bodies, which may again involve military allies such as Japan.

Repositioning the Alliance for the Final Frontier

There are good reasons to think Japan and the United States will align their space enterprises under the U.S.-Japan alliance. Both have foundational space capabilities underpinned by independent industrial bases that link economics and defense. Both share an understanding of space-related threats, whether accidental or deliberate. Japan is also aligning with U.S.-led civilian, commercial, and military ventures in space in concrete ways and is poised to expand on those building blocks under its new national security posture. 

That said, the text of the 1960 U.S.-Japan security treaty has not changed even as the world has evolved. Further, from the perspective of international law, the U.S.-Japan alliance is stuck in terrestrial mode. Three elements can more equally help to reposition the alliance to meet challenges in the space domain and to signal an allied vision of space security that draws others in.

  1. Strengthen capability architectures.
    One immediate priority area involves building an integrated SDA architecture that enables foundational safety for all space operations carried out by any and all stakeholders. Aside from illuminating what is where at what coordinates at any point in time, this architecture can layer in allied spacecraft for RPOs. More immediately, RPO-enabled spacecraft can be designed to serve civilian, commercial, and defense interests threatened by orbital debris; they can also be repurposed to safeguard operations from LEO and geosynchronous orbits on to cislunar space and celestial bodies.

    Another priority area involves configuring constellations of small satellites that would compile big data to more effectively support national and allied decisionmaking about how, when, and where to act. This emerging frontier has already changed prospects for commercial observation of virtually all human activities on a global and persistent basis, meaning not just national security but also economic, social, climate, and other pressures that threaten countries and the international order.

    At this early stage, a final priority area involves activating dialogue on the nexus of space technologies and systems with others, such as cybersecurity, autonomous robotics, quantum encryption and information networks, and the expanding fusion of artificial intelligence with satellite data. These are critical civil-commercial-military intersections whose impacts will stretch across all domains, continents, regions, and countries.
  2. Develop legal and policy clarity.
    In spirit, it is easy enough to extend Article V of the U.S.-Japan security treaty to jointly “act to meet the common danger” in space. But for joint actions to even be considered credible in practice, the two allies need to build interpretive clarification on just what an “armed attack against either Party in the territories under the administration of Japan” means in the context of outer space. The two allies will have to clarify and operationalize who is protecting what assets and with what justifications under existing international space law and their military pact. If redlines are drawn, the allies need to be prepared to defend them. This legal and policy clarity should be a top defense priority for both allies and can be an important driver of how capability architectures will be divided and sustained, with equal responsibility for both.
  3. Synchronize diplomatic communications.
    Capabilities and clarifications that legitimize the cause of allied space security will require aligned diplomacy. Japan’s space diplomacy has shown its staunch support of U.S. leadership by joining the U.S. commitment in April 2022 not to conduct destructive, direct-ascent ASAT missile testing. In reverse, the United States can fortify regional building blocks in partnership with Japan. Japan has been leading the Asia Pacific Regional Space Agency Forum (APRSAF) for decades, a platform the two allies can leverage to pursue allied interests in the wider region to influence the course of space-related science and socioeconomic development for a wide range of interested countries. More loftily, they can craft shared understanding of norms and other behavior in space through APRSAF’s National Space Legislation Initiative. As Japan has concretely shown, this is an interactive and consensus-building exercise of networked Asia-Pacific experts, whose voices can be communicated via UN venues to the international space community at large. Such initiatives are tethered to the principles of the 1967 Outer Space Treaty, and this will be diplomatically advantageous in a domain marked by many new and varied stakeholders with their own interests in a changed world order.

Saadia M. Pekkanen is a professor, founding director of the Space Law, Data and Policy Program at the School of Law, and founding director of the QUAL Program at the Henry M. Jackson School of International Studies at the University of Washington.

This project is made possible with support from the Government of Japan.

Saadia M. Pekkanen

Professor and Founding Director of the Space Law, Data and Policy Program; Founding Director, QUAL Program at the University of Washington