Russia’s defense ministry has reported plans to build up military infrastructure on the Kuril Islands, a region under dispute between Russia and Japan. Claimed by Japan as their “Northern Territories,” the four southernmost Kuril islands north of Hokkaido have been the primary obstacle to a formal peace treaty between Russia and Japan since the end of World War II when the Soviet Union claimed ownership. Now, the islands are mainly of concern as a proxy for the U.S.-Russia conflict, as Russia recognizes Japan’s strong alliance with the United States. From the perspective of the Russian regime, American access to the islands could threaten their security.

“Japan’s alliance cooperation with the United States tends to be perceived in Russia within the context of its own confrontation with the United States,” wrote Andrey Gubin, an associate professor with the Far Eastern Federal University for the East Asia Forum website. “Washington is a powerful ally for Japan with the potential to change the status quo in Northeast Asia, something Moscow would like to avoid.”

The four islands in contention offer a strategic advantage for whichever nation administers them. Controlling Iturup, Kunashir, Shikotan, and Habomai allows Russia to claim the Sea of Okhotsk as internal waters and gives them access to passageways for large ships. If Japan occupied these islands, it could limit the passage of the Russian military. Russia has also long speculated that handing the islands back to Japan would lead to the establishment of U.S. naval bases, given Japan’s close relationship with the United States.

In the tense game of potential nuclear warfare, a Kuril island base concerns Russia because a military installation so close to their mainland could host a defense system against Russian missiles, or permit the deployment of U.S. or Japanese missiles. This is especially pertinent following the U.S. withdrawal from, and the overall demise of, the I.N.F. Treaty under Donald Trump in 2019.

National pride and prestige are also factors on both sides. Some Russians, especially nationalists and those from Sakhalin Oblast where the Kuril islands are located, strongly oppose the potential transfer of any islands, including the transfer of Habomai and Shikotan proposed in the 1956 agreement between the U.S.S.R. and Japan. In addition, returning authority over the islands to Japan would heighten the pressure for Russia to return Crimea to Ukraine, an issue of central concern to their foreign policy. Putin’s government likely aims to boost its popularity with the domestic Russian audience by taking a strong stance in relationships with countries like Japan and the United States.

Japan has long laid claim to the islands, despite Russian control. Some Japanese politicians fear that giving up this claim would be an embarrassment that would go against Japanese public opinion. When Russian prime minister Mikhail Mishustin visited the Kurils in late July, Tokyo summoned Russia’s ambassador to Japan in an angered response. Russia retaliated by summoning Japan’s ambassador. Despite a history of pride tied to the refusal to forfeit the claims to the islands, only 44% of Japanese people supported returning any of the islands in a 2019 poll.

Russia’s militarization of the Kurils could be an effort to gauge the reaction of the United States, which has taken a stance on a somewhat similar situation of disputed territories between Japan and China. As per Article 5 of the U.S. and Japan’s security treaty, the United States recognizes any attacks on Japanese soil, which includes the Senkaku Islands administered by Japan but claimed by China, as attacks upon American soil, and is committed to responding appropriately. This agreement has not been extended to the Kurils, and the U.S. has thus far remained non-committal on the dispute over the region – a position which leaders in Russia would like to see the U.S. continue to hold.

A large part of the negotiations and discussions that have taken place between Russian and Japanese leaders thus far have involved engaging in joint economic development projects in the Kurils. Russia and Japan can agree that continuing down this path is in the interest of both parties. Hopefully, this will encourage a dialogue that could result in the long-awaited peace treaty. It seems unlikely that Russia will comfortably give up its hold on the islands, and the United States would be remiss to needlessly increase tensions with the nation by coming to Japan’s defense. Instead, the international community should support negotiations between the two nations, which must take each other’s domestic dialogues around the islands into account, and also emphasize the shared desire for a peaceful resolution to the decades-old dispute.