Russian President Vladimir Putin visited Iturup, a Japan-claimed island at the end of the Kuril chain near the island of Hokkaido, Russian media said on Thursday, a day after major naval drills and a missile firing by ally North Korea.
Moscow and Tokyo never signed a formal World War Two peace treaty as the main hurdle was the unresolved territorial dispute over the islands, which Japan calls the Northern Territories.
On the trip, which state news agency TASS described as Putin's first in person to the island chain, he visited the Yasny fish-processing plant on Iturup, after overseeing the navy drills in Russia's far east.
Japan's foreign minister protested against Putin's visit on social media.
"The northern territories, including Etorofu, are Japan's inherent territory both historically and based on international law," said Toshimitsu Motegi. "Japan strongly protests this visit."
Vesti TV channel images showed Putin in a dark suit, standing in a room looking at two large tuna and halibut on a table, as two officials spoke about fishing and the migratory behaviour of fish. He also stopped to try local fish roe.
"What lovely weather you have there, just like a resort!" Putin told a group of Iturup locals. "And we thought you arranged this!" a woman, who appeared to be in her 30s, joked back.
The visit follows Wednesday's firing of a ballistic missile by ally North Korea, towards waters off the east of the Korean peninsula, days ahead of major joint military exercises by Seoul and Washington long denounced by Pyongyang.
(Reporting by Jekaterīna Golubkova, Kiyoshi Takenaka and Kantaro Komiya in Tokyo; Editing by Jacqueline Wong and Clarence Fernandez)
