Russian President Vladimir Putin recently visited the islands of Iturup, which is administered by Russia but claimed by Japan as part of its “Northern Territories,” along with Kunashiri, Shikotan and the Habomai islets.

Putin’s trip, his first to the disputed island chain, included visits to a school, hospital and fish-processing plant. Japanese Prime Minister Sanae Takaichi called the visit “absolutely unacceptable,” while Foreign Minister Toshimitsu Motegi summoned Russia’s ambassador and lodged a formal protest. The visit was unpopular with the Japanese public as well, and large numbers of Japanese citizens have spoken out against it.

President Putin’s visit threatened to reopen one of Asia’s oldest unresolved territorial disputes and sharply worsened already tense relations between Moscow and Tokyo. The islands are strategically important as well as symbolic. Their location between Japan and Russia’s Far East gives them military value, and Moscow has strengthened its forces there over the years. The surrounding waters are also rich fishing grounds. For Japan, therefore, the dispute touches national sovereignty, historical memory and modern security.

Japanese anger is rooted in history. Under the 1855 Treaty of Shimoda, Japan and imperial Russia placed their boundary between Etorofu and Uruppu, leaving Etorofu on the Japanese side. In 1875, Japan relinquished its claims to Sakhalin in exchange for Russian recognition of Japanese control over the Kuril chain farther north. The situation changed dramatically at the end of World War II.

The Soviet Union entered the war against Japan in August 1945 and occupied the southern islands after Japan announced its surrender. Moscow has controlled them ever since.

The islands’ legal status remains disputed. Japan argues that Etorofu, Kunashiri, Shikotan and Habomai were historically separate from the Kuril Islands that Japan renounced under the 1951 San Francisco Peace Treaty. Russia maintains that its sovereignty was settled by the outcome of World War II.

A 1956 Soviet-Japanese declaration restored diplomatic relations and contemplated transferring Shikotan and Habomai to Japan after a peace treaty, but the broader disagreement prevented such a treaty from ever being concluded.

That history made Putin’s personal appearance especially provocative. It was not merely a routine domestic trip. By walking through local institutions and meeting residents, the Russian president visibly demonstrated Moscow’s administration of territory Tokyo says belongs to Japan.

The timing also mattered. Japan has imposed sanctions on Russia over the invasion of Ukraine, while Russia has suspended peace-treaty negotiations and hardened its position on the islands.

Tokyo’s unusually forceful response reflects a broader deterioration in the Asia-Pacific security environment. Japan’s 2026 defense white paper warns of strengthening military cooperation among Russia, China and North Korea, while Japan itself is increasing defense capabilities in response to what it regards as a worsening regional threat environment.

Against that background, Putin’s visit looks less like an isolated historical dispute and more like part of a wider contest over borders, military power and the regional order.

The episode suggests that relations between Japan and Russia are moving farther away from compromise and deeper into the strategic rivalry now reshaping Northeast Asia. That makes the dispute a test of whether postwar settlements can still be managed through diplomacy.