China Coast Guard vessels have been spotted near the Japanese-administered Senkaku Islands for a record 353 days this year, the Japan Coast Guard (JCG) said Sunday, as Beijing continues to ramp up its activities near the tiny islets that it also claims.

As of midnight Monday, four China Coast Guard vessels had been confirmed inside the so-called contiguous zone just outside Japan’s territorial waters around the Senkakus, the JCG said.

“The circumstances in the waters surrounding the Senkaku Islands remain severe and unpredictable,” Seishiro Sakamoto, director-general of the JCG's 11th regional headquarters, said a statement.

The JCG will continue to monitor the situation and “respond calmly yet firmly,” ensuring that “no change goes unnoticed,” he added.

The entry of Chinese government vessels into Japan’s contiguous zone — which extends from the edge of territorial waters 12 nautical miles (22 kilometers) from shore for an additional 12 nautical miles — surpassed the 352 days recorded last year, setting a fresh high since such navigations were first confirmed in 2008.

As of Saturday, China Coast Guard vessels had entered Japan’s territorial waters near the Senkakus 39 times during 2024, a figure in line with recent years. Notably, 18 of these incidents involved attempts to approach Japanese fishing boats, matching the 2021 record for the highest number of such confrontations.

The JCG has indicated its intention to strengthen its response, including by increasing the number of large unmanned aerial vehicles it operates from three to five.

Japan firmly rejects China’s claim to the islands, which are located some 400 km west of Okinawa Prefecture’s main island. The waters around the islets, which Japan nationalized in 2012, are rich in fish stocks and are also believed to be home to oil and gas deposits.

China and Japan have seen several confrontations in the area in recent months.

In October, the China Coast Guard claimed that a Japanese fishing vessel had "illegally entered" what it said were its territorial waters around the islands, known as Diaoyu by Beijing. The vessel was warned to leave the area. In June, Tokyo protested to Beijing after four Chinese vessels — all armed with cannons — entered Japanese territorial waters around the Senkakus for the first time.

In a bid to avert unexpected clashes, the two Asian powers agreed to create a military hotline after years of negotiations, with the first call having taken place last year.

Activity near the Senkakus has been overshadowed in recent months by the growing presence of the Chinese military even closer to Japan, including the August violation of Japanese territorial airspace for the first time. Days later, a Chinese Navy survey ship entered Japanese waters off Kagoshima Prefecture, the 13th such entry since last September.