Russian President Vladimir Putin yesterday visited a disputed island close to Japan prompting a strong condemnation from Tokyo, which said his actions had made any improvement of relations between the countries difficult.

The island, known in Russia as Iturup and in Japan as Etorofu, is one of four in the Kuril chain close to Japan’s main islands seized by Moscow in the days after Japan’s surrender in World War Two. Tokyo has maintained its claim to them, making their return a condition for concluding a formal peace treaty that would unlock closer economic ties.

It “hurts the feelings of the Japanese people and is absolutely unacceptable,” Prime Minister Sanae Takaichi said in a televised statement. “We hope that the Russian side will take the seriousness of this matter fully to heart,” she added.

Ties between Moscow and Tokyo soured after Putin ordered the full-scale invasion of Ukraine in 2022. Japan joined other nations in condemning the attack and imposing sanctions on Russia.

Putin’s visit to the island comes two days before Japan marks 81 years since its surrender ended World War Two, and a day after North Korea fired a missile into the sea separating it from Japan ahead of joint drills by Seoul and Washington.