Chinese coast guard vessel 1307, seen here in August 2025, entered Japan's territorial waters near the Senkaku Islands on Nov. 16, 2025. (Japan coast guard)

The Chinese coast guard entered waters Japan claims as its territorial limit around the Senkaku Islands over the weekend, less than 10 days after Japan’s prime minister warned Tokyo would use military force if China attacked Taiwan.

Four Chinese vessels crossed into the 12-mile zone east of the Senkakus around 10:15 a.m. Sunday, according to a Japan coast guard statement released the same day.

The uninhabited Senkakus — five islets and three rocky outcrops — lie about 105 miles east of Taiwan and 254 miles west of Okinawa. They are administered by Japan but also claimed by China and Taiwan.

The Japan coast guard said the Chinese vessels, which carried deck-mounted machine guns, were warned to leave the area. The ships exited after about two hours, moving south, according to a second news release.

A “larger contingent of Japanese coast guard vessels” blocked the Chinese vessels and used radio and electronic message boards to warn them to leave, a coast guard spokesman said by phone Monday. He declined to specify how many Japanese vessels were sent.

China announced its activity on social media. “This was a rights protection cruise carried out by the China Coast Guard in accordance with the law,” the service said Sunday on its official Weibo account.

Japanese Chief Cabinet Secretary Minoru Kihara on Monday called the intrusion “a violation of international law” and “unacceptable.” Japan has lodged a complaint through diplomatic channels, he said at his regular press briefing in Tokyo.

The incident is the first in the Senkakus since Prime Minister Sanae Takaichi said during a Nov. 7 parliamentary session that a Chinese attack on Taiwan would constitute “an existential threat” requiring Japan to use military force.

The comments triggered a sharp response from China’s consul general in Osaka, Xue Jian, who wrote on X that “we have no choice but cut off that dirty neck that has been lunged at us without hesitation,” according to The Associated Press. The post was later deleted.

On Friday, Vice Minister of Foreign Affairs Takehiro Funakoshi summoned Chinese Ambassador Wu Jianghao to lodge a complaint about Xue’s remarks, the Foreign Ministry said. China’s Ministry of Defense said Wu, in turn, filed a complaint over Takaichi’s comments.

Chinese President Xi Jinping has vowed to unify self-governing Taiwan with the mainland, by force if necessary.

U.S. Ambassador to Japan George Glass voiced support for Tokyo in a Sunday post on X, saying, “the U.S.-Japan alliance is steadfast in its resolve to preserve peace and stability across the Taiwan Strait” and tagging Wu and Xue.

“We strongly oppose any unilateral attempts to change the status quo of the region through force or coercion,” Glass wrote.

Chinese vessels have entered Japanese territorial waters near the Senkakus 25 times this year, the Japan coast guard spokesman said. The previous intrusion occurred on Oct. 15.

Some Japanese government officials can speak to the press only on condition of anonymity.