Chinese Buoy Placed in Japan’s Exclusive Economic Zone Removed

On February 11, the Yomiuri Shimbun (Japan’s largest newspaper by circulation), citing an announcement by the Japan Coast Guard, reported that a large buoy that China had placed in Japan’s exclusive economic zone (EEZ) near the Senkaku Islands (administered by Okinawa Prefecture, and known in China as the Diaoyu Islands) in July 2023 had been removed.

The buoy had been placed by the Xiangyanghong 22, a large work vessel belonging to the East China Sea Bureau of China’s Ministry of Natural Resources, in waters some 80 kilometers to the northwest of Uotsuri Island, part of the Senkaku Islands. With a height and diameter of approximately 10 meters, it bore the designation “China Ocean Observation Buoy QF212” on its surface, and is believed to have been transmitting data such as water temperature and ocean currents via satellite communications.

After confirming the deployment of the buoy near the Senkaku Islands in July 2023, the Japan Coast Guard issued a navigation notice indicating that “Yellow light buoys have appeared in northeastern Taiwan” to warn vessels operating in the area. At around 1 p.m. on February 11, however, the warning was lifted.

In recent years, China has deployed multiple buoys to the sea surrounding Japan. In June 2024, the Xiangyanghong 22 placed a buoy in the Shikoku Basin area of Japan’s continental shelf, to the north of Okinotorishima Island. Then, in December 2024, it was confirmed that China had placed another buoy, displaying “China Meteorological Administration” and other markings, inside Japan’s EEZ to the south of Yonaguni Island, part of Okinawa Prefecture. In December 2024, during a visit to China, Japan’s Minister of Foreign Affairs, Takeshi Iwaya, pass on a request for the immediate removal of the buoys to his Chinese counterpart, Foreign Minister Wang Yi.

At a press conference held on February 11, China’s Foreign Ministry Spokesperson Guo Jiakun commented on the buoy installed in waters near the Senkaku Islands, asserting that installation of the buoy was “consistent with both domestic and international laws,” adding that the buoy had “completed its task at the site” and that “relevant Chinese agencies have implemented technical adjustments,” acknowledging that the buoy had been moved.

At a press conference the next day, Chief Cabinet Secretary Hiroshi Hayashi acknowledged that the buoy placed near the Senkaku Islands had been relocated, but added that he would refrain from speculating on the background or events leading up to the relocation, avoiding any comment on the Chinese government’s response. However, he did say that the buoys placed in water around Yonaguni Island and in Japan’s EEZ south of Yonaguni Island in Okinawa Prefecture remained in place, adding that Japan would “take every opportunity to strenuously demand their immediate removal” by the Chinese government.

Marine scientific research (MSR) conducted without the consent of a coastal state within its EEZ violates Article 246, Paragraph 2 of the United Nations Convention on the Law of the Sea, and it is a violation of international law. If China had not removed the buoys it had placed inside Japan’s EEZ, Japan would have been able to remove the buoys to halt violations of international law in accordance with the law on the responsibilities of states for wrongful acts.

China began expanding its presence in the South China Sea from the 1970s and in the East China Sea starting in the 1980s, and has been expanding into the western Pacific since the turn of the century. China has frequently conducted marine scientific research (MSR) in waters surrounding Okinotorishima Island, which are located in the center of the western Pacific.

In recent years, such as on July 9, 2020, a Japan Coast Guard patrol vessel confirmed that the Chinese research vessel Dayang Yihao had deployed observation equipment into the sea in Japan’s EEZ, roughly 310 kilometers north-northwest of Okinotorishima Island. MSR conducted without the consent of a coastal nation within its EEZ contravenes Article 246, Paragraph 2 of the United Nations Convention on the Law of the Sea, and is a violation of international law. The Japan Coast Guard issued warnings and demands to the Chinese research vessel, communicating that “research activities conducted within the exclusive economic zone of Japan without the prior permission of Japan are not allowed. Please halt the research activities.” The research vessel repeatedly collected the observation equipment, relocated to other areas within Japan’s EEZ, and again placed observation equipment in the sea. Following these activities, the vessel left Japan’s EEZ on July 27, 2020.

The western Pacific includes the island of Guam, which hosts a nuclear submarine base for the U.S. Navy. By claiming that Okinotorishima Island is not an island but a rock, China is seeking to reject Japan’s exercising of its jurisdiction over its EEZ in the sea around the island, and along the continental shelf. This is intended to allow China to freely and extensively collect data on the seafloor topology, water temperature and ocean currents in the local waters, and in doing so effectively block the deployment of U.S. naval assets in an emergency situation involving Taiwan.

For Japan, it is crucial that China be prevented from freely conducting research activities in Japan’s EEZ and continental shelf. This will require Japan to restrict MSR within its EEZ and continental shelf near Okinotorishima Island through domestic laws, and to step up patrols of Japan’s EEZ and continental shelf near Okinotorishima Island in light of the MSR-related provisions of the UN Convention on the Law of the Sea.

TSURUTA Jun is an associate professor at Meiji Gakuin University.