Russia's navy has conducted simulated enemy attacks around the disputed islands, drawing sharp criticism from Japan. The exercises come amid continuing tensions between the two countries, following Vladimir Putin's visit to the islands last week.

Russia's Pacific Fleet said on Thursday that it had fired Bastion surface-to-ship missiles from Etorofu, the largest of the disputed islands, simulating an attack on enemy vessels, hitting all targets at a distance of approximately 300 kilometers.

According to official data, the drills involved a nuclear-powered submarine and a guided-missile cruiser. Putin's first visit to Etorofu last week led to a tit-for-tat summoning of ambassadors in Tokyo and Moscow. Japan refers to these islands as the Northern Territories or the Four Northern Islands, while Russia considers them part of the Kuril Islands.

Japan's Foreign Minister Toshimitsu Motegi said on Thursday during a trip to Oman: "We cannot tolerate moves to strengthen military power on the Four Northern Islands because they go against our country's stance [on the territories]."

The territorial dispute over the islands dates back to the 19th century. The Soviet Union seized them from Japan at the end of World War II.

The Russian fleet's exercises began on August 4, and Japan was informed in advance that they would include live-fire drills. Japan lodged a protest against the large-scale maneuvers on August 5.

According to Russia's TASS news agency, the drills involved "approximately 60 surface ships, submarines, and support vessels, about 30 aircraft, helicopters, and unmanned aerial systems of the Pacific fleet's naval aviation, as well as over 13,000 service members."

Putin observed some of the exercises from the Varyag on August 12 as part of his trip to the disputed islands and to Sakhalin, the large undisputedly Russian island north of Hokkaido. Speaking aboard the flagship, Putin said: "The region is unfortunately becoming increasingly prone to conflict, with NATO seeking to gain a foothold here and the emergence of new military and political blocs. There are efforts and plans to deploy new weapons systems here, which creates threats for our country."

The Russian drills are scheduled to continue through August 29.