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An Overview of Japan’s Counterspace Strategy

By Doug Messier
Parabolic Arc
April 26, 2020
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Global Counterspace Capabilities:
An Open Source Assessment

Secure World Foundation
April 2020

Full Report

The following excerpts from the report summarize Japan’s counterspace capabilities.

Country Summary

Japan has long been a well-established space actor and its space activities have historically been entirely non-military in nature. In 2008, Japan made a change to its constitution to enable national security-related activities in space and more recently, government officials have begun to publicly speak about developing various counterspace capabilities or developing military SSA capacity.

Japan is currently undergoing a major reorganization of its military space activities and development of enhanced space situational awareness (SSA) capabilities to support military and civil applications. While Japan does not have any acknowledged offensive counterspace capabilities, it is actively exploring whether to develop them. Japan does have a latent anti-satellite (ASAT) capability via its missile defense system but has never tested it in that capacity.

Direct Ascent Anti-satellite (DA-ASAT) Technologies

Japan has no designated DA-ASAT systems under development or in operation. However, it does have the Standard Missile (SM)-3 sea-based ballistic missile defense interceptor, which the United States demonstrated in 2008 could be used to intercept a satellite with only a software modification.

A similar software modification might enable Japan to have a DA-ASAT capability against satellites 600 km or lower, although Japan has never tested the SM-3 in that capacity nor expressed a desire to develop it.

Japan is also working with the United States on the 3rd stage rocket motor and nose cone of the SM-3 Block 2A interceptor, which is intended to be a more capable hit-to-kill missile interceptor. The SM-3 Block 2A has a faster burnout speed than its earlier iteration and thus could theoretically reach any satellite in LEO if used in a DA-ASAT role. It is planned to be tested during 2020.

Co-Orbital Technologies

In August 2019, the Japanese government announced that it was deliberating whether to develop a satellite that could be used to intercept foreign threat satellites. The goal would be to make a decision in the coming fiscal year so that if Japan decided to go ahead with such a capability, it could be launched by the mid-2020’s.

According to a senior Ministry of Defense official, this is because Japan’s Self-Defense Forces (SDF) “don’t have any defense capability for the satellites.” To develop this counterspace capability, the Japanese government reportedly will also research different ways in which to interfere with threat satellites, including cyber attacks, RFI, and robotic arms. It is not known whether this future counterspace capability will be defensive or offensive.

Electronic Warfare

The Japanese government has considered developing jamming capabilities that could be used against both airborne warning and control system (AWACS) planes (possibly by the mid-2020’s) and then foreign satellites.

In August 2019, the Japanese MoD released a budget request for FY2020 that included a request for a 4.0-billion yen ($38-million) program for a “study on electromagnetic disruption system” and purchasing equipment that could detect when its satellites are being electromagnetically interfered with.

Japan has also announced steps to reorganize its military space activities. In January 2020, during remarks at the 60th anniversary of the Treaty of Mutual Cooperation and Security Between the United States and Japan, Prime Minister Shinzo Abe noted the need to make the U.S.-Japan alliance more “robust” and “to make it a pillar for safeguarding peace and security in both outer space and cyberspace.”

Abe also announced at a session of the Diet in January 2020 that Japan will “drastically bolster capability and systems in order to secure superiority.”

During that speech, he announced that Japan would be establishing its Space Domain Mission Unit (SDMU) in April 2020, with the goal of having it be fully operational by 2022. The SDMU will initially have 20 personnel assigned to it, but is expected to grow to 100 personnel by FY 22, and will carry out SSA and strive to protect Japanese satellites via counterspace capabilities.

The SDMU will be part of Japan’s Air Self-Defense Force and is intended to work with both U.S. Space Command and JAXA.

Potential Military Utility

Japan currently possess very limited potential counterspace capabilities. Japan could potentially use its limited SSA capabilities to detect, track, and target a modified SM-3 missile as a DA-ASAT against an adversary satellite in LEO, perhaps with additional tracking assistance and intelligence from the United States. Japan likely possesses the technological foundations to conduct EW against space capabilities, but the military utility and effectiveness of its ability to do so is unknown

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