Chinese Coast Guard and Research Vessels Advance Around Japan in 2026, Increasing the Burden on the Japan Maritime Self-Defense Force

In September, China's research vessel "Kexue" was confirmed in waters approximately 70 kilometers north of Ishigaki Island. While it appears to be a single voyage, reports indicate that since 2026, activities of Chinese public vessels and research ships in waters around Japan have noticeably increased. This suggests that the challenges faced by the Japan Maritime Self-Defense Force (JMSDF) and the Japan Coast Guard (JCG) cannot be measured solely by the number of vessels.

Significance of Research Vessel Operations

Research vessels are not armed ships. However, they can collect data on shipping routes, water depth, seabed topography, tidal currents, and electromagnetic environments. This information is relevant not only for submarine operations but also for planning anti-ship missiles, unmanned aerial vehicle activities, and monitoring sea lines of communication (SLOC). While it cannot be immediately concluded that the operations of the Kexue were military surveys, the investigations conducted in the southwestern islands near the Senkaku Islands and Taiwan must be evaluated by separating capability from intent.

Practical Pressures on the JMSDF

The Ministry of Defense has indicated that China is attempting to unilaterally change the status quo in the maritime and airspace around Japan. The issue lies in the fact that research vessels, public vessels, naval ships, and aircraft appear as separate incidents. The current division of responsibilities, where the JCG handles law enforcement and the JMSDF provides supplementary surveillance from the rear, is reasonable during peacetime. However, if operations continue, the wear and tear on personnel, patrol aircraft, and communication networks will accumulate. The deterrent effect of the Japan-U.S. alliance is also insufficient if it only involves sharing information; it is crucial that the JCG, JMSDF, and U.S. forces can grasp the situation on the same nautical charts and timelines.

Blind Spots Beyond the Gray Zone

For China, the activities of research vessels could serve as a means to gauge Japan's reaction time and monitoring patterns without crossing the threshold of military conflict. The more Japan is pressed for legal evaluations of individual incidents, the greater the risk of losing sight of the overall cumulative effect. Conversely, if everything is labeled as military provocation, it unnecessarily narrows the role of the JCG. What is needed is to integrate the tracks of research vessels, the deployment of naval and coast guard forces, and surrounding aerial activities into a single SLOC monitoring diagram.

In my view, the weakness in the defense of the southwestern islands lies not in the range of missiles but in the mechanism for sharing information about approaching activities, including vessels that appear unarmed, at a speed that allows for timely political judgment. When Chinese activities increase, Japan's first defeat will not be the loss of maritime territory but rather the handling of peacetime anomalies as "normal operations."

Reference Information

• Indo-Pacific Defense FORUM, China's intrusions into Japanese waters surged in 2026
• Japan Ministry of Defense, China's Activities in East China Sea, Pacific Ocean, and Sea of Japan