FILE - In this handout photo released by Russian Defense Ministry Press Service, Chinese troops march during the Vostok 2022 military exercise at a firing range in Russia's Far East, on Aug. 31, 2022. Beijing has been increasing its military cooperation with Moscow and has been taking part in the multilareal joint drills “Vostok 2020” held in Russia's Far East since late August.(Vadim Savitsky/Russian Defense Ministry Press Service via AP, File)

TOKYO (AP) — Japan has protested to Russia over multinational military exercises being conducted on Russian-held islands claimed by Japan, and is seriously concerned about shooting drills by Russian and Chinese warships off Japan's northern coast, an official said Monday.

Beijing has been increasing its military cooperation with Moscow, and has been taking part in the multinational “Vostok 2020” drills since late August at a number of locations in Russia's far east.

Japanese Chief Cabinet Secretary Hirokazu Matsuno criticized Russia for holding exercises on two of the four disputed islands, which Japan calls the Northern Territories, in the Kuril chain off Japan's northernmost main island of Hokkaido. It was not clear whether China was part of the exercises on the disputed islands.

He said Japan’s Defense Ministry spotted six Russian and Chinese warships firing machine guns into the Sea of Japan about 190 kilometers (118 miles) west of Cape Kamui on Hokkaido on Saturday.

“Japan will continue to monitor the movements of these ships with serious concern, and will take all possible measures to conduct warning and surveillance activities in the waters surrounding Japan,” Matsuno said at a news conference.

China’s Ministry of National Defense said in a statement Sunday that China participated in air, ground and naval exercises as part of the exercises. It said a Chinese naval tactical team conducted joint exercises with Russia in the Sea of Japan, including one designed to destroy drifting mines.

Japan has raised concern about growing tensions in Asia following Russia’s invasion of Ukraine, fearing that the war is emboldening China's already assertive military activities in East Asia, especially around Taiwan, which China claims. Japan is currently revising its national security strategy and defense guidelines to significantly bolster its military capabilities to reinforce its deterrence.

After the joint firing exercise, the warships, including a Chinese guided missile destroyer, a frigate and a supply ship and three Russian frigates, crossed the Soya Strait between the Japanese islands of Honshu and Hokkaido. The Chinese warships had crossed Tsushima Strait in southwestern Japan on Aug. 29, the ministry said.

Japan has repeatedly sought to regain sovereignty over the disputed islands, which Moscow seized in the closing days of World War II. The dispute has prevented the two countries from signing a peace treaty formally ending their World War II hostilities. Russia earlier this year announced it has suspended peace talks with Japan to protest Tokyo’s sanctions against Moscow over its war in Ukraine.

News from © The Associated Press, 2022