Japan said Thursday it "strongly protests" Russian President Vladimir Putin's visit to a disputed island.

According to TASS news agency, Putin has visited the Far Eastern Kuril Island of Iturup after attending the final stage of the Pacific Fleet drills in Yuzhno-Sakhalinsk.

In a statement on social media X, Japanese Foreign Minister Toshimitsu Motegi said "the Government of Japan strongly protests this visit."

Russia and Japan are involved in a territorial row over Iturup, which Japan calls Etorofu, and the other three islands off Japan's northern prefecture of Hokkaido. The four islands that are under Russia's control are called the Northern Territories in Japan and the Southern Kurils in Russia.