Japan has lodged a protest after Russia notified Tokyo that it would conduct military exercises near Russian-held islands off Hokkaido starting Wednesday.

According to Japanese government officials, Russia said that live-fire drills would be held until Monday in waters off Kunashiri and Etorofu islands, two of the four Russian-held islands claimed by Tokyo. The four islands are called the Northern Territories in Japan.

Through diplomatic channels, Japan protested that it cannot accept Russia¡¯s moves to strengthen its military around the Northern Territories, including the latest exercises.

Russia has stepped up military activity around the Northern Territories recently. In late July, it announced missile exercises by its Pacific Fleet along the coasts of the Chishima and four Russian-held islands, collectively called the Kuril Islands in Russia.

The four islands were seized from Japan by the Soviet Union near the end of World War II. The territorial issue has prevented Tokyo and Moscow from concluding a postwar peace treaty.