Japan’s Space Program: Shifting Away from “Non-Offensive” Purposes?

Concerns about the United States’ readiness and ability to fulfill its security commitments have led Tokyo to enact security reforms to enhance its value as an ally while moving toward a more autonomous defense posture to prepare for the worst-case scenario of abandonment. This has transformed the Japanese space program from one based on the principle of peaceful use of space to a program aimed at ensuring national security through non-offensive means.
The security track of Japan’s space program currently aims at boosting the combat prowess of the Self-Defense Forces (SDF) in accordance with the non-offensive principle, and at maintaining in all circumstances the ability to use space-based assets for this purpose. Therefore, the country is not militarizing outer space beyond what is necessary to guarantee the proper functioning of the SDF.
Information-gathering and maritime domain awareness devices, positioning services and military communications satellites provide Japan with better understanding of its environment, help anticipate and tackle threats, and allow greater interoperability between the SDF services. And, because national security increasingly depends on space operations, space situational awareness has taken prominence in Japan’s space program as a way to protect space assets against orbital debris and anti-satellite weapons.
Compared to the United States, China and Russia, Japan is still inhibited by domestic constraints when it comes to military-related affairs, and thus the use of space for security purposes. But, although Japan’s space program is today almost purely non-offensive in nature, the intra-alliance hedging strategy implies a potential weaponization of space, beyond the non-offensive principle. This offensive use of space could materialize through the acquisition of strike capabilities, and the development of Japan’s own anti-satellite weapons or of active defense systems for space assets.

Asie.Visions, French Institute of International Relations (Ifri): https://www.ifri.org/en/publications/notes-de-lifri/asie-visions/japans-space-program-shifting-away-non-offensive-purposes