The captain of the JS Suzutsuki was replaced after the Japanese destroyer intruded into Chinese waters on July 4, 2024. (Japan Maritime Self-Defense Force)

The captain of a Japanese warship that reportedly sailed into Chinese waters this summer has been replaced, according to Japan’s defense minister.

Defense Minister Minoru Kihara, at a news conference Tuesday, said the skipper of the Japan Maritime Self-Defense Force destroyer JS Suzutsuki was replaced in July but declined to identify the officer or say why the move was made.

Kihara also declined to confirm that the destroyer intruded into Chinese waters on July 4.

“Not only in the Maritime Self-Defense Force, but also in the Ground and Air Self-Defense Force, transfer of personnel happens on multiple occasions, but we do not release the reason for each transfer, and it is the same for this transfer too,” he said.

Tokyo told Beijing the ship inadvertently sailed into Chinese territorial waters within 12 nautical miles of the coast of Zhejiang province, Kyodo News reported Monday, citing unnamed diplomatic sources.

A Maritime Self-Defense Force base questioned the Suzutsuki after noticing it had entered Chinese waters early on July 4. The destroyer’s captain responded that he was “not aware” the ship had sailed into an “off-limits area,” Kyodo reported.

The officer was named captain of the Suzutsuki in May, a Ministry of Defense spokesman said by email Wednesday. He declined to answer questions about whether the vessel entered Chinese waters on July 4.

Some Japanese government officials are required to speak to the media only on condition of anonymity.

The ministry started an investigation of the ship’s captain in response to the incident, Kyodo reported July 11.

China’s Maritime Safety Administration on July 3 issued a warning that a live-fire exercise would run July 4-5 in Hangzhou Bay, bordered to the south by Zhejiang and north by Shanghai. The Suzutsuki was monitoring the drill when Chinese vessels urged it to leave the area, but instead it sped up and sailed into Chinese waters for about 20 minutes before leaving, Kyodo reported July 11.

Under China’s Maritime Traffic Safety Law, foreign vessels are required to give notice and provide a variety of information before entering Chinese waters. Under the more broadly accepted United Nations Convention on the Law of the Sea, foreign warships are generally allowed innocent passage through territorial waters provided they don’t pose a threat.

Chinese vessels frequently intrude into Japanese waters near the Senkakus, islets about 105 miles east of Taiwan that are administered by Tokyo but claimed by Beijing and Taipei.

Earlier this month, a Chinese aircraft carrier sailed between Japan’s westernmost island of Yonaguni and nearby Iriomote, entering the country’s “contiguous zone,” according to the Defense Ministry.