Tokyo — On Tuesday, the Japanese military announced the deployment of a surveillance aircraft and a naval vessel after detecting a Russian submarine near a southwestern island close to Taiwan.

The Russian Kilo-class submarine was located approximately 50 kilometers (31 miles) south of Yonaguni Island, which is Japan’s westernmost territory situated just east of Taiwan, according to a statement from the Japanese Joint Staff.

The submarine was reported to be navigating northeast, accompanied by a Russian naval ship, between Yonaguni and the adjacent Iriomote Island. This marked the first instance of a Russian submarine being spotted in this region, as stated by the Joint Staff.

In response, Japan’s Self-Defense Forces launched a combat support vessel and deployed a P-3 surveillance aircraft for reconnaissance and warning duties. The Japanese authorities emphasized that the Russian naval vessels did not violate Japan’s territorial waters during their passage.

This incident followed a report from the Philippine military that also identified a Kilo-class Russian submarine operating in the South China Sea just a day earlier.

Japan has expressed mounting concerns regarding China’s increasing military presence in the waters and airspace surrounding the nation, leading to a significant enhancement of its defensive measures, particularly on remote islands critical to its defense framework. The nation is equally apprehensive about Russia’s military activities and their collaborative operations with China.

Recently, a Chinese frigate sailed eastward near another southwestern Japanese island, Miyako. Furthermore, in September, the Chinese aircraft carrier Liaoning, along with two destroyers, transited between Yonaguni and Iriomote, entering Japan’s contiguous zone, which lies outside its territorial waters but remains an area where Japan can assert some regulatory control over maritime activities.