CAMP FOSTER, Okinawa — Chinese coast guard vessels have been warning Japanese military aircraft to leave airspace over and around the Japanese-administered Senkaku Islands in the East China Sea, according to Japanese media.

Kyodo News reported Saturday that Chinese vessels have warned Japan Self-Defense Force aircraft several times since January, saying the Japanese are violating China’s territorial airspace.

The two countries square off frequently over the five small, uninhabited islands and three reefs off the northeast tip of Taiwan. Tokyo frequently accuses Beijing’s coast guard of harassing Japanese fishing boats there and sends its coast guard to intercede.

The latest warnings call on Japanese aircraft to leave Japanese airspace, going beyond previous warnings to leave the airspace immediately surrounding the island group, Kyodo News reported, citing anonymous government officials.

Tokyo has lodged a protest with Beijing through diplomatic channels, according to Kyodo, but a spokesman for the Ministry of Foreign Affairs’ China and Mongolia Division declined to say if they protested or not when reached by phone Tuesday.

“The Japanese government has always lodged a protest whenever China makes its own claims regarding the Senkaku Islands,” the spokesman said.

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

Defense Minister Minoru Kihara also declined to disclose that information at a Tuesday morning press conference. He said it is to protect Japan’s surveillance activities and intelligence capabilities.

“The Senkaku Islands are an inherent territory of Japan without any doubt, both historically and under international law,” he said. “Indeed, the Senkaku Islands are effectively under Japan’s control. Whenever China makes its own claims regarding the Senkaku Islands, the Japanese government has always protested in an appropriate and strict manner.”

The Senkakus, though relative specks in the open sea, are among several sites where China acts aggressively to assert territorial claims that other nations regard as illegal.

Chinese leader Xi Jinping, during a November visit to a Chinese coast guard command in Shanghai, highlighted the necessity to “constantly strengthen” Beijing’s claim on the islands, Kyodo reported in January, citing unnamed sources.

During Kihara’s October visit to the Pentagon, Defense Secretary Lloyd Austin repeated the “ironclad” U.S. commitment under the Japan-U.S. Security Treaty “to defend all of Japan, including the Senkaku Islands.”

U.S. Ambassador to Japan Rahm Emanuel in a January post on X, formerly Twitter, said Chinese leadership had announced a plan to keep ships in and around Japan’s Senkaku Islands for 365 consecutive days.

Chinese ships have been spotted in the islands’ contiguous zone every day so far this year, according to the Japan coast guard’s website. Chinese ships were spotted there on 352 days in 2023.

The Senkakus are about 100 miles northeast from Taiwan’s northern coastline and about 250 miles west of Okinawa. The islands are strategically situated near key shipping lanes, rich fishing grounds and potentially significant oil and natural gas reserves, according to the CIA World Factbook website.