Russia has summoned Japan's ambassador to Moscow to protest “anti-Russian” comments made by Prime Minister Sanae Takaichi following Russian President Vladimir Putin’s recent visit to one of the disputed Kuril Islands. Putin’s visit last Thursday to Iturup Island, the largest in the chain, marked the first time a Russian president had visited the territories.

The visit prompted Japan to summon Russia’s ambassador in protest earlier in the week. Japanese Prime Minister Takaichi described Putin’s visit as “grave” and “absolutely unacceptable.” She asserted that the Northern Territories, as they are known in Japan, are historically and legally part of Japanese territory. Takaichi also stated that the visit has intensified anti-Russian sentiment in Japan and complicated the long-term restoration of relations between the two nations.

Japan’s ambassador to Moscow departed a 25-minute meeting at Russia’s Ministry of Foreign Affairs on Tuesday without making any public statements. Russia’s Foreign Minister Sergey Lavrov had previously criticized Takaichi’s remarks, calling them a violation of "decency" and accusing Tokyo of pursuing a "militaristic line."

Relations between Russia and Japan have been strained for decades due to the dispute over the Kuril Islands. The Soviet Union seized the islands in 1945, expelling the Japanese population. The territorial conflict over the southern Kurils—Iturup, Kunashir, Shikotan, and the Habomai Islands—has prevented the signing of a post-World War II peace treaty between the two countries.

The diplomatic exchange underscores the persistent tensions over the islands, which have a significant geopolitical and historical context. The Soviet seizure and subsequent administration of the islands have created a lasting legacy of disagreement.

Relations between Moscow and Tokyo have further deteriorated since Russia’s full-scale invasion of Ukraine in 2022. Japan has aligned with other G7 nations in imposing sanctions on Russia and providing financial and non-lethal military aid to Ukraine. Notably, Japan has been indirectly supporting Ukraine's air defense by supplying domestically produced Patriot missiles to the United States, helping to replenish U.S. stockpiles depleted by aid to Kyiv.

Analysts suggest that Putin's visit to the Kurils may serve as a signal to Japan against deepening its support for Ukraine. This could involve direct supplies of Patriot missiles to Kyiv or increased cooperation with NATO. Although Japan has recently eased its pacifist policies, allowing for the export of lethal weapons, it is still restricted from directly supplying such equipment to nations engaged in conflict.

The ongoing dispute over the Kuril Islands remains a significant obstacle to a comprehensive peace treaty and highlights the complex geopolitical landscape in the region, further complicated by current international events.