As if the world did not have enough geopolitical flashpoints, the dormant 150-year-old territorial dispute between Russia and Japan over the Kuril Islands has resurfaced. The latest phase of the bilateral spat began in mid-August 2026 when Russian president Vladimir Putin visited four islands that the Kremlin had seized during the closing days of World War 2. Sanae Takaichi, Japan’s prime minister, denounced Putin’s actions as “absolutely unacceptable” and the Foreign Ministry formally chastised Russia’s ambassador in Tokyo. Moscow countered that Japan was making unfounded claims on Russian territory.
The 1951 San Francisco peace treaty formally ending the war between the Allies and Japan attempted to resolve postwar territorial disputes. In that treaty, Tokyo renounced its claim to the Kurils but also contended that the four southernmost islands were distinct from the Kuril chain and, therefore, were still part of Japan’s territory. Since the Soviet Union never signed the treaty at all, the Kuril issue remained unresolved.
The dispute has continued to be a volatile, emotional topic with populations in both countries. Russia calls the islands the “Southern Kurils” whereas Japan refers to the four islands as the “Northern Territories,” and any use of the “wrong” name in public can trigger a surprisingly intense response in either country. The topic appears to have greater salience, though, in Japan. Large demonstrations have occurred periodically in Japanese cities to protest Russia’s ongoing occupation. Foreign Minister Toshimitsu Motegi reiterated that his country “strongly protests” Putin’s visit. He added that the “Northern Territories are Japan’s inherent territory both historically and from the perspective of international law.”
Bilateral animosity over the issue appears to be getting worse. As Moscow’s relations with the Western powers deteriorated in recent years, Russia has bolstered its military presence on the Kurils. Control of the islands gives Russia year-round access to the Pacific for its fleet based in Vladivostok, because the strait between the southern islands does not freeze in winter.
Putin used his trip not only to reassert Russia’s territorial claim but also to protest Japan’s ongoing sanctions against Russia over the invasion of Ukraine. Indeed, Putin’s arrival coincided with large-scale Russian military exercises in the neighboring seas. Takaichi warned that the visit “has further hardened Japanese public sentiment toward Russia and has made it more difficult to restore bilateral relations in the medium to long term.”
There have been mounting signs of worsening relations between Moscow and Tokyo regarding the disputed islands and an array of other issues. On October 17, 2026, Russian officials informed Japan of new planned bombing drills on the Kurils. On October 14, Russian authorities detained a prominent Japanese journalist on espionage charges.
Takaichi’s government already faces tense relations with China over another chain of disputed islands. Coast Guard vessels from the two countries have clashed near those islands, called the Senkakus in Japan and the Diaoyus in China, several times since Takaichi took office. One ugly incident took place in December 2025, and an even more serious episode occurred in July 2026. The uninhabited Senkaku island chain is both claimed and administered by Japan but is also claimed by China. Located between Taiwan and Okinawa, the islands have long been a source of friction between Beijing and Tokyo because of their strategic location. Both commercial and military interest in the area also has spiked because there may be substantial deposits of oil and natural gas reserves beneath the East China Sea.
There is a significant risk that the United States could become entangled in the disputes involving either the Kurils or the Senkakus. That is especially true since there is a mutual defense treaty with Japan. Thus far, U.S. leaders have tried to finesse the Senkakus territorial issue. Washington has stated publicly on several occasions that the United States continues to support Japan’s administration of the islands. However, Washington has not taken an official position on the larger question of sovereignty. In practical terms, that stance means that Japan will control the Senkakus indefinitely. Any PRC attempt to forcibly dislodge Tokyo’s control would be considered an act of war against an official U.S. ally.
Washington’s position with respect to the dispute between Russia and Japan over possession of the Kurils is not ambiguous. U.S. officials back Tokyo’s position that all the islands are Japanese territory. “The United States remains unwavering in its support of its most important ally and in its recognition of Japanese sovereignty over the Northern Territories,” George Glass, The U.S. ambassador to Tokyo, said in August 2026, during Putin’s visit. Using the Japanese name for the islands put additional emphasis on Washington’s stance.
Experiencing a simultaneous deterioration of its relations with Russia and China could prove especially ominous for Japan. Cooperation between Beijing and Moscow has been growing steadily since the Ukraine crisis erupted. The two countries have even held several joint military exercises in the Pacific. They are now in a position to put substantial pressure on Japan.
Takaichi’s government would be wise to adopt a more cautious, nuanced strategy to alleviate the hostility coming from at least one source. It would be difficult to achieve a rapprochement with China, since the two countries have some major, substantive disputes on an array of issues.
Conversely, Tokyo’s quarrel with Russia is both less severe and less central to important Japanese interests. Therefore, it should be easier to ease tensions with the Kremlin. Much of Moscow’s anger with Japan is because of Tokyo’s ill-advised support for NATO’s proxy war backing Ukraine against Russia. Japan gains nothing of value by being entangled in a war on the other side of the world. Withdrawing its support from U.S. and NATO policy on Ukraine would be a good first step for improving Japan’s relations with Russia. Such an initiative might even lead to Moscow’s greater flexibility on the islands issue left over from World War II. It is at least worthwhile for Japanese leaders to explore that option. Meanwhile, the United States should adopt a more neutral stance on the islands dispute.
