Fake ship signal off the Senkakus traced to Chinese naval port area during PLA's Taiwan drill

A cargo ship that did not exist appeared on public ship-tracking data inside the territorial waters of the Senkaku Islands, known in Taiwan as the Diaoyutai, for almost two weeks around China's large-scale military drill encircling Taiwan last December, Japan's Sankei Shimbun reported on 16 October 2026. Taiwan's Liberty Times carried the findings on Saturday 17 October.

The fake Automatic Identification System (AIS) signals ran from early on 19 December 2025 to early on 1 January 2026, Japan time, and carried a vessel name built around an English obscenity aimed at Japan. The phantom track entered the territorial sea, passed between Uotsuri and Kita-kojima, turned back in the contiguous zone south of Uotsuri and at one point showed the ship anchored about 155 metres north of the island.

When patrol ships of the Japan Coast Guard's 11th Regional Headquarters in Naha went to check, there was nothing there. The Sankei had reported at the time that the identifier used, an MMSI number beginning with 415, matched no country code and was absent from the International Maritime Organization database, and that a European Space Agency radar satellite image of the area showed no hull. MarineTraffic treated the signal as spoofing and hid it.

The newspaper's analysis of MarineTraffic data found the false signals were picked up mostly around Zhoushan in China's Zhejiang province, an area dotted with ports believed to serve the People's Liberation Army's Eastern Theater Command, which is responsible for operations against Taiwan. Who actually sent the signals, and on whose orders, has not been established.

The timing is what drew attention. The Eastern Theater Command opened its Justice Mission-2025 drill around Taiwan on 29 December. The phantom ship first appeared about 10 days earlier and disappeared shortly after the exercise ended on 31 December.

Bonji Ohara, a senior fellow at the Sasakawa Peace Foundation and a former Japanese defence attache in Beijing, said the forged identifier pointed to an organised operation, and that because Zhejiang also hosts fishing ports used by China's maritime militia, militia involvement could not be ruled out. Atsushi Toyama, a former deputy head of territorial-waters security at the 11th Regional Headquarters, said Chinese coast guard ships have long switched their AIS on and off for strategic effect, and suggested the aim may have been to confuse Japan, probe how the coast guard responds and drain its resources by forcing it to check.

Aki Mouri, an associate professor at Doshisha University, noted that AIS spoofing by Chinese vessels has been reported elsewhere, including a suspicious signal in Taiwan that impersonated the aircraft carrier Liaoning. She said China, as a party to the Safety of Life at Sea convention, should establish the facts and prevent a repeat. The Japan Coast Guard is adding more SeaGuardian drones, and the government plans to begin research on uncrewed vessels from next fiscal year to tighten surveillance of nearby waters.

For Taipei the episode is a reminder that the maritime picture around a PLA drill can be polluted before the first warship sails. Taiwan's coast guard and navy, like Japan's, lean on AIS to sort traffic in the busy waters north-east of Taiwan, and a cheap spoofing campaign that forces patrol ships to chase ghosts would fit Beijing's habit of grey-zone pressure that stops short of force.