Aug. 13 (UPI) — Japan issued a stern rebuke to Moscow on Thursday after Russian President Vladimir Putin visited a disputed chain of islands off Hokkaido that were occupied by Russia at the end of World War II.

Foreign Minister Toshimitsu Motegi in a post on X strongly condemned Putin’s visit to Etorofu Island — Iturup to the Russians — the third of the four southernmost Kiril Islands about 80 miles northeast of the Japanese mainland, saying it was part of Japan.

“We have received reports today that Russian President Putin has visited Etorofu Island. The Northern Four Islands, including Etorofu Island, are an inherent part of Japan’s territory — both historically and under international law — and Japan strongly protests this visit,” said Motegi.

Russia’s state-run TASS news agency said Putin visited Iturup as part of a trip to Russia’s Sakhalin region.

On the island, he met with Sakhalin region Governor Valery Limarenko, toured a fish-packing factory, visited a secondary school and spoke with residents.

Prior to visiting Iturup, Putin attended the final stage of drills of Russia’s Pacific Fleet off Yuzhno-Sakhalinsk.

TASS said it was his first visit to the islands which Russia calls the Kurils, and claims as part of its far eastern Sakhalin province, and Japan calls its Northern Territories.

The last senior Russian government official to visit the area was in 2021 when Prime Minister Mikhail Mishustin visited Iturup.

The dispute is over the four islands at the southern end of the volcanic archipelago with Russia claiming them under the post-World War II world map that came out of the 1945 Yalta Agreement, months before the war ended, first in Europe, and then in the Pacific.

Japan’s position is that Yalta only contained a non-binding recommendation that the islands should go to Russia, that it was not a party to the agreement and that Russia’s invasion of the Kirils in 1945 was in breach of a neutrality pact signed by the two countries in 1941.

The long-running dispute means that as far as Russia and Japan are concerned, World War II hostilities technically never ended as they never formally signed a peace treaty.