Japan faces a strategic challenge that does not begin with a missile launch or a naval confrontation. The more likely scenario is a gray-zone incident: a severed submarine cable, a hacked port communications system, or a disrupted fuel supply chain. In such cases, attribution may take days or weeks, and the line between accident, crime, and coercion remains blurred. Tokyo has recognized this threat, but the structure to address it remains incomplete.
Three recent developments illustrate the breadth of the problem. KDDI's cable-laying and repair capacity, Tokyo's intervention in the proposed acquisition of Makino Milling Machine by MBK Partners, and the rare-earth magnet recycling project involving Daikin, Shin-Etsu Chemical, Hitachi, and Tokyo Eco Recycle all belong to different policy domains—digital infrastructure, industrial equipment, and material recovery. Yet together, they point to a single reality: Japan's civilian industries and defense systems depend on the same infrastructure, and gray-zone disruption will hit both simultaneously.
Infrastructure as a Defense Asset
Japan's National Security Strategy explicitly identifies gray-zone situations, cyberattacks on critical civilian infrastructure, and information warfare as pressures that blur peacetime and contingency. The Defense Buildup Program further treats the defense production and technology base as part of defense capability, acknowledging that advanced civilian technologies shape future operations. Recent fiscal year 2026 defense materials designate selected airports and seaports for smoother Self-Defense Forces and Japan Coast Guard use, with road access to SDF bases added from fiscal year 2025. These are important steps, but designation alone does not guarantee resilience.
What Tokyo must decide now is which civilian systems are most exposed to gray-zone disruption and which failures would most quickly cascade into both defense operations and civilian life. Japan cannot harden every port, cable, supplier, road, airport, cloud system, and industrial firm equally. Priority should go to systems that must keep operating before Tokyo has all the information required for a decision. If an airport transport system is hacked, a port operating platform is compromised, or fuel logistics are interrupted, local authorities and private operators cannot freeze until attribution is clear.
Cables and Connectivity
Japan is a major Indo-Pacific cable node. A CSIS report notes that Japan has more than 20 international submarine cable landing stations and around 30 active or announced international cable systems. Those cables give Japan digital importance, but they also create a physical resilience problem. A damaged cable must be reached by a vessel, handled by trained crews, and restored through arrangements that often sit in private or commercial hands.
Japan has domestic strengths in this area. KDDI Cable Infinity works on construction and repair of domestic and international telecommunications submarine cables. A cable break may first appear as a commercial repair problem rather than a national security incident. That makes cable resilience part of Japan's broader access challenge, rather than an isolated telecommunications issue. Access and connectivity can allow Japan to keep moving during the early phase of disruption. Recovery then depends on the industrial capacity to repair what has been damaged.
Industrial and Material Resilience
Tokyo's intervention in MBK Partners' proposed acquisition of Makino Milling Machine illustrates a shift in how Japan views its broader defense apparatus. The case shows a more expansive view of defense-adjacent industry, where companies outside the traditional defense sector can still become relevant to national security. METI lists machine tools and industrial robots among Japan's specified critical products, alongside permanent magnets, aircraft parts, semiconductors, storage batteries, cloud programs, natural gas, critical minerals, and ship parts. The firms and inputs that sustain defense capability often sit in ordinary industrial systems before they appear in security planning.
Material supply also matters because resilience depends on what Japan can recover from its own civilian economy. The rare-earth magnet recycling project involving Daikin, Shin-Etsu Chemical, Hitachi, and Tokyo Eco Recycle provides a new pathway for material recovery. These companies are developing a system to recover rare-earth magnets from commercial air-conditioner compressors and return them to magnet production. This further illustrates the connection between civilian commercial networks and defense-relevant industrial needs.
All of this demonstrates that Tokyo cannot treat gray-zone resilience as a traditional defense-industrial problem alone. A crisis below the threshold of open conflict may affect civilian infrastructure before it reaches the systems usually classified as defense. That makes ports, cables, repair capacity, and material recovery part of the operational environment.
Tokyo has taken important steps within individual sectors, but gray-zone disruption will move across them. A holistic framework should build from these existing policy decisions and connect civilian infrastructure and commercial firms to Japan's defense-industrial needs. Two concrete steps would help. First, Japan should map defense-adjacent dependency chains for ambiguous disruption rather than clean wartime scenarios. The map should show where the same authorities, repair assets, and emergency procedures serve both civilian and military systems. Second, Tokyo should establish clearer protocols for private-sector operators to continue functioning during gray-zone incidents, reducing the time lost to uncertainty.
Japan's approach to gray-zone resilience is not just about military readiness. It is about ensuring that the country's civilian economy—its cables, ports, factories, and recycling networks—can keep running when the line between peace and conflict is deliberately obscured. For an archipelagic state dependent on global connectivity, that is the real test.
