SECURITYDecember 4, 2025

Kuril Islands become a Sino-Russian fortress against Japan

Stefan Hedlund

Reading time: 10 min

The Kuril Islands dispute, long a bilateral issue between Russia and Japan, is increasingly shaped by Moscow’s dependence on Beijing.

Jan. 1, 1997: Former Japanese residents of Shikotan Island prepare altars and wreaths at their ancestors’ gravesites in the Kuril Islands. Expelled in the late 1940s after Soviet occupation, they were permitted a brief return visit in 1997 under a visa-free exchange program. © Getty Images

In a nutshell

The Kurils secure Russia’s Pacific Fleet and Sea of Okhotsk nuclear bastion
Dispute heightens Japan’s vulnerability in the event of a Taiwan contingency
China drops support for Japan’s claim, aligning firmly with Moscow
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At the far eastern edge of the Russian Federation lie the Kuril Islands, a sparsely populated chain of islands that separates the Sea of Okhotsk from the Pacific Ocean. Spanning approximately 1,300 kilometers, from Japan’s northernmost island of Hokkaido to the southern tip of Russia’s Kamchatka Peninsula, these islands have long been a focal point of territorial dispute between Moscow and Tokyo. Recently, this conflict has gained prominence in the arena of great-power politics.

Strategic flashpoint: Kurils in great power rivalry

The Kuril Islands are strategically positioned at the gateway to Russia’s Pacific Fleet basing areas. This is particularly true for the Kamchatka Peninsula, where the Russian Empire first established its naval presence in the Pacific. Even more crucial is the access to the fleet headquarters in Vladivostok, located on the western shore of the Sea of Japan. Ships that set out for patrols in the Pacific Ocean must navigate through the narrow La Perouse Strait, which lies between Hokkaido and the Russian Sakhalin Island, before passing through the Kuril Islands. Given the recent deterioration in relations between the Kremlin and Western nations, Hokkaido’s military vulnerability has become more apparent.

Facts & figures

The Kuril Islands

The Kuril Islands have gained attention since Russia’s full-scale invasion of Ukraine in 2022. China is now backing Russia in its confrontation with Japan over the islands. This support from Beijing is tied to Moscow’s endorsement of China’s ambitions in Taiwan. As joint Sino-Russian naval operations become a key strategy for deterring Japan and South Korea from stepping up their support for Taiwan, Russia, with a vantage point near the northern shores of Hokkaido, gains a significant advantage. Control over the island chain not only offers Russia critical forward listening posts but also ensures safer routes for its aircraft.

Consequently, the issue of who holds legal rights to the islands has become increasingly crucial.

Historical roots of the dispute

The foundation was laid in the 1855 Treaty of Shimoda, which granted Japan sovereignty over the four southernmost islands: Kunashir, Iturup, Shikotan and the Habomai group (known in Japanese as Kunashiri, Etorofu, Shikotan and Habomai, respectively, and collectively called the Northern Territories). In the decades that followed, fluctuations occurred regarding the tradeoff rights to Sakhalin, a large Russian island north of Japan.

Their current status was determined by a decision Joseph Stalin made at the end of World War II. Taking advantage of Japan’s defeat, he ordered the seizure of the four islands by force. Japanese locals were expelled, and Russian settlers moved in. The Kuril Islands have been under continuous Russian administration since 1945. As this occurred after Japan had already surrendered to the United States, Tokyo has never recognized the annexation as legitimate.

Due to domestic sensitivities, no Japanese government has been able to make any concessions. As a result, Japan and the Soviet Union have never concluded a formal peace treaty to end World War II. The 1956 Joint Declaration normalized diplomatic relations but left the territorial dispute unresolved.

The issue has been complicated by the ambiguity of international law regarding territorial claims to the islands. The San Francisco Peace Treaty, signed in 1951, stated only that Japan had relinquished the “Chishima Islands,” without explicitly mentioning the four disputed islands. Japan continues to claim that the four southernmost islands are not part of the Kurils but rather constitute the Northern Territories. It further maintains that because the Soviet Union was not a signatory to the San Francisco Treaty, the treaty cannot be used to justify Russian claims to the islands.

At a meeting in Moscow in November 1998, Russian President Boris Yeltsin and Japanese Prime Minister Keizo Obuchi committed to resolving the dispute over the islands within 14 months. In a joint Moscow Declaration, they aimed to finalize a peace treaty by the end of 2000. Yeltsin was forced to resign in 1999, and the effort was abandoned.

Under President Vladimir Putin, there was speculation of various deals, ranging from the return of the two southernmost islands to a compromise that would grant Japan sovereignty while allowing Russia to remain responsible for administration. Beyond the fundamental issue of national sovereignty, the Kurils are also crucial for accessing valuable fishing grounds and rare-earth mineral deposits. However, the question of sovereignty has consistently taken precedence over any potential economic deal.

The last time a compromise seemed possible was in 2018, when President Putin met with then Prime Minister of Japan Shinzo Abe. After returning to office in 2012, Abe sought to improve relations with Moscow by building a personal relationship with Mr. Putin. By 2017, they had met 20 times. Their bargaining positions had softened, with Japan indicating that it was willing to accept a step-by-step deal in which Shikotan and the Habomai group would be returned first, followed by the larger islands of Iturup and Kunashir, provided Russia recognized Japanese sovereignty over all four. Ultimately, negotiations collapsed.

Jan. 22, 2019, Moscow, Russia: Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe shake hands during a press conference. The Japanese leader was at the Kremlin to discuss the dispute over the Kuril Islands. © Getty Images

The Kremlin’s militarization of the Kuril Islands

Russia’s staunch opposition to any territorial concessions was increasingly tied to its ambition to regain its status as a great power by revitalizing its weakened military. After launching a heavily funded rearmament program in 2009, the Kremlin began militarizing the disputed islands. Although this occurred after Russia’s invasion and annexation of Crimea – and drew little international attention – the strategic consequences were profound.

The first steps were taken in late 2015, when Russian forces stationed on the islands were provided with a Soviet-era Tor-M2U surface-to-air missile system. In 2017, a Bastion anti-ship missile battalion was deployed to Iturup, and a Bal anti-ship missile battalion to Kunashir. These deployments were followed by significant construction activity on both islands, including the erection of barracks to house an estimated 3,500 troops of the 18th Machine-Gun Artillery Division. In December 2020, air defense capabilities were enhanced with the deployment of an S-300 missile battery to Iturup.

The Putin regime is determined to transform the islands into a barrier that can both threaten Hokkaido and defend approaches to the Sea of Okhotsk.

While Moscow claimed these actions were purely defensive efforts to protect Russian territory, Tokyo expressed concern that the P-800 Oniks supersonic missile fired by the Bastion system could threaten much of Hokkaido, enabling the interception of ships in large parts of its coastal waters.

Russia has also increased military activity on islands further north in the Kuril chain. In December 2021, additional Bastion launchers were set up on Matua, situated in the middle of the Kuril Islands. Furthermore, on Paramushir, which lies even further north, a new airstrip was constructed alongside extensive barracks complexes.

The Putin regime is determined to transform the islands into a barrier that can both threaten Hokkaido and defend approaches to the Sea of Okhotsk. The updated Russian maritime doctrine, presented during Navy Day celebrations in St. Petersburg on July 31, 2022, specifically mentioned that both the Sea of Okhotsk and the Kuril Islands would be protected “by all means.”

Moscow’s full-scale invasion of Ukraine has elevated the islands’ geopolitical importance. The war has produced three major ripple effects for the Kuril Islands dispute.

First, Ukraine has officially recognized Japan’s claim to the Northern Territories as legitimate. This was done in October 2022 through a decree that officially acknowledged the Kuril Islands as Japanese territory temporarily occupied by Russia. Considering that Ukraine has already carried out strikes on various targets in the Russian Far East, particularly against military bases linked to serious war crimes in Ukraine, it is quite plausible that Russian military installations on the Kuril Islands could also come under attack.

Feb. 7, 2019, Kyiv, Ukraine: Ukrainian activists participate in a rally supporting Japan in its territorial dispute with Russia over the Kuril Islands. They demanded that the Ministry of Foreign Affairs formally recognize the Kuril Islands as Japanese territory occupied by Russia. © Getty Images

Many of the “Russians” who settled on these islands following Stalin’s land grab were Ukrainians. Some observers in Japan have suggested that a considerable number of current residents on the southern islands are descendants of Ukrainians who were forcibly relocated there by the Soviets after 1945. Estimates from pro-Ukrainian and Japanese sources even claim this figure could be as high as 60 percent. This connection could motivate some of them to support Ukrainian covert operations against Russian military sites.

The second point is that Japan was compelled to follow the lead of the major Western countries in condemning Russian aggression and enacting tough sanctions. This effectively ended Abe’s olive branch diplomacy, which had involved responding to the annexation of Crimea with only mild sanctions. Moscow’s response to the escalation was harsh, indicating that all discussions on economic cooperation and a potential peace treaty were suspended indefinitely. Moreover, President Putin chose not to attend Abe’s state funeral.

The deterioration of relations cast a shadow over the Russian Vostok-22 war games held in September. Staged every four years under the supervision of Russia’s Eastern Military District, these exercises took place in the waters and coastal areas around the Sea of Okhotsk and the Sea of Japan. With Russian military units, including Pacific Fleet marine infantry, heavily involved in the war in Ukraine, China’s participation held political significance.

Scenarios

Least likely: Japan secures legal sovereignty over the Kuril Islands

The least likely scenario is that Japan finally gains legal recognition for its claim to sovereignty over the contested islands. The only way this might happen is if the Russian Federation splits, leaving its Far East isolated. Japan could then step in as a protector of the Northern Territories that would otherwise be in serious trouble. However, achieving international recognition of sovereignty would still be a long shot, given expected objections from other regional powers.

Somewhat likely: Russia collapses, China steps in as protector of its assets

A somewhat more probable scenario is that a collapse of the Russian Federation presents China with a difficult choice about how best to protect its own interests. Beyond securing continued access to energy and other raw materials, China might choose to strengthen its military stance against Japan by acting as a protector for Russian military installations on the Kuril Islands, including but not limited to the Northern Territories.

Most likely: Russia declines economically and becomes China’s vassal

The most probable scenario is that, as Russia faces increasing economic decline due to its war in Ukraine, it gradually becomes a vassal state under China’s control. Beijing may then adopt a firmer stance on Taiwan while tacitly encouraging more assertive Russian actions on the Kuril Islands and near Hokkaido. As a result, Japan will need to reassess the robustness of its security guarantees with the U.S.