A Chinese naval destroyer conducted live-fire exercises near Japan’s remote Okinotori Island while operating alongside other Chinese warships and a Russian frigate, prompting Tokyo to raise concerns over maritime safety and growing military cooperation between Beijing and Moscow.

Japan’s Joint Staff said its Maritime Self-Defense Force detected four vessels sailing northeast about 330 kilometres southwest of Okinotori at approximately 2 a.m. on Sunday.

The group included a Chinese Renhai-class guided-missile destroyer, a Luyang III-class guided-missile destroyer, a Fuchi-class supply ship and a Russian Steregushchiy-class frigate.

Japanese forces later confirmed that the Luyang III-class destroyer conducted live-fire training approximately 180 kilometres southwest of the island.

Tokyo said this marked the first time it had publicly disclosed a Chinese live-fire exercise inside waters that Japan considers part of its exclusive economic zone. Japan formally protested to China over the drill, citing risks to the safety of vessels navigating nearby, although it acknowledged that the activity did not violate international law, according to reuters.

A Japanese destroyer monitored the vessels and collected information about their activities, while air and maritime surveillance operations were also deployed.

China disputes Japan’s claim to an exclusive economic zone surrounding Okinotori, arguing that the formation is a rock rather than an island and therefore cannot generate such a maritime zone under international law.

The incident comes as China and Russia intensify joint naval and air operations around Japan. Tokyo has responded by expanding surveillance and strengthening its military presence across its southwestern island chain amid growing concerns over regional security.