Russia’s Navy Shows Its Reach Around Japan’s Southwestern Islands

President Vladimir Putin’s mid-August visit to the Kuril Islands, his first as Russia’s leader, inflamed a decades-old territorial dispute with Japan and drew worldwide attention to the two countries’ border in the northern Pacific. But over the past several years, Russian forces have been increasingly active far to the south, around Japan’s southwestern-most islands, in a demonstration of the Russian military’s reach and its willingness to challenge its rivals on its own and alongside China.

The dispute centers on the southernmost islands in the Kuril chain, which Japan calls its Northern Territories and says the Soviets seized illegally after Tokyo’s surrender at the end of World War II. Thousands of former Japanese residents of the islands are still alive, and resolving the dispute is a high priority for Japanese leaders. Russia’s activity on the islands, especially its military buildup, is therefore a sensitive issue for Tokyo.

Putin’s visit to the island Russia calls Iturup and Japan calls Etorofu on August 13 struck a chord with Tokyo not only for its location but also for its timing. Putin first traveled to Sakhalin Island – his first visit there in 13 years – to observe drills by Russia’s Pacific Fleet, part of a month-long series of exercises in the area that Japan protested. His visit also came days after the anniversary of the atomic bombings of Hiroshima and Nagasaki and days before the anniversary of Japan’s World War II surrender announcement.

Putin’s Kuril visit coincided with another Russian movement much farther south. The same day, Japan’s Defense Ministry reported that it had observed a Russian navy Improved Kilo-class submarine and a search-and-rescue vessel sailing north between the two Japanese islands closest to Taiwan, Yonaguni and Iriomote. That was one of at least 14 transits by Russian vessels around Yonaguni so far in 2026, a considerable increase over recent years.

A review of releases by the Japanese military’s Joint Staff from the past five years shows no such transits in 2021 and just two in 2022, both between Yonaguni and Iriomote. 2023 saw another two transits between Yonaguni and Iriomote, followed by a jump to six transits – five between Yonaguni and Iriomote and one between Yonaguni and Taiwan – in 2024. After a dip to four Yonaguni-Iriomote transits in 2025, there have been 11 transits between those islands and three between Yonaguni and Taiwan so far this year, the most recent on September 25.

Activity around Japan’s Southwest Islands is a growing concern for Tokyo. China has increased its military operations there since the early 2010s, training to sail and fly around and through that island chain. Chinese activity near Yonaguni and its neighboring islands, known as the Sakishima Islands, has also picked up in recent years, a sign of Beijing’s interest in familiarizing its forces with the area around Taiwan. In late 2024, a Chinese aircraft carrier sailed between Yonaguni and Iriomote for the first time, drawing a formal protest from Tokyo. In response, Japan has increased its military presence on the islands, opening bases for radars, electronic-warfare units, and surface-to-air and anti-ship missiles on Yonaguni and Ishigaki, which is just east of Iriomote.

Some Russian transits around Yonaguni appear to be part of routine voyages to and from the Pacific Fleet’s bases near Vladivostok. There may be a practical reason to use that route. “For ships coming south from Vladivostok through the East China Sea, the passage between Yonaguni and Iriomote provides a convenient way into the Philippine Sea without going farther northeast through the Miyako Strait,” Thomas Shugart, an adjunct senior fellow at the Center for a New American Security and a retired U.S. Navy officer, said in an email. Shugart said Russia’s navy may also have a political reason to avoid the more direct route to the South China Sea through the Taiwan Strait: “Given Beijing’s sensitivity to foreign naval transits of the Strait, routine Russian use could invite the observation that even the Russians treat it as an international waterway.”

But the behavior of other Russian vessels around Yonaguni appears more likely to be “deliberate signaling toward Japan,” Shugart said. In some cases, Russian vessels have loitered in the area, perhaps to monitor Japanese activity and response measures. In its annual “Defense of Japan” report, Japan’s Defense Ministry singled out an unusual operation in January this year, in which a Russian Vishnya-class intelligence-gathering ship was seen “navigating for an extended period” around the Sakishima Islands and Okinawa. Joint Staff releases showed that over the course of 12 days the vessel sailed south between Taiwan and Yonaguni and circled the Sakishima Islands before crossing the Miyako Strait and lingering southeast of Okinawa for three days. “Notably, this marked the first confirmed instance of such a vessel circumnavigating the Sakishima Islands,” the report said.

The ministry’s report linked recent activity around the Sakishima Islands with a years-long uptick in Russian operations around Japan, “including exercises and training likely intended to verify the results of military reforms” and operations farther afield that are likely meant to keep the U.S., Japan, and others “in check.”

Since Russia launched its full-scale invasion of Ukraine in February 2022, its navy “has been continuously involved in active deterrent operations against the United States and its Western allies,” Alexey Muraviev, a professor at Edith Cowan University in Australia who studies Russian military strategy, said in an interview late last year. Regular deployments to Southeast Asia, where Moscow has sought to bolster its military ties, are a part of those operations, Muraviev said, but they also reflect continued concerns about the US and its allies, especially Japan. “Russia clearly sees Japan as a military risk – partially because of its alignment with the United States through security and defense ties, partially because of [the] unresolved territorial dispute,” Muraviev said.

Russia’s activity around Japan also shows its deepening military ties with China, which has become a more important partner amid Moscow’s international isolation following its invasion of Ukraine. Over the past several years, Sino-Russian bomber and naval patrols have incorporated a wider range of ships and aircraft, including diesel-electric submarines and nuclear-capable bombers, and traveled farther, sometimes circling the Japanese archipelago. During their most recent naval patrol, in July, their ships transited east through the Miyako Strait, headed north along Japan’s east coast, and then sailed west through the Vries Strait, which separates the Kuril Islands that Japan claims from the rest of the chain. The route demonstrated the two navies’ increasing ability to operate through “strategic waterways,” Chinese experts told state media.

Russia has also echoed China’s criticism of what it calls Japan’s “militarism,” a line of attack that Beijing started pushing late last year, likely in an attempt to stoke backlash to Japan’s growing military investments and regional security role. Russian officials returned to that talking point in the weeks following Putin’s visit to the Kuril Islands, lashing out at Japan for hosting a military exercise with the U.S. around Hokkaido, the Japanese main island closest to the Kurils, and objecting to its proximity to Russian territory. “The Japanese side was firmly informed that provocative military activity near our country’s far eastern borders is categorically unacceptable,” Russian Foreign Ministry spokeswoman Maria Zakharova said on September 1.