Russia’s Pacific Fleet has conducted a missile test off a group of Russian-held islands claimed by Japan, as a territorial dispute between the two countries deepens.

The test was announced on August 20 amid an intensifying row following Russian President Vladimir Putin’s visit to the disputed area the previous week.

According to Kyodo News, it was not immediately clear when the test took place. The announcement came after Russia’s Foreign Ministry summoned Japanese Ambassador to Russia Akira Muto over Tokyo’s protest against Putin’s visit.

Putin travelled to Etorofu, the largest of the four islands collectively known as the Northern Territories in Japan and the Southern Kurils in Russia, on August 13.

The Pacific Fleet said a unit equipped with the Bastion surface-to-ship missile system conducted the test. The system is deployed on Etorofu.

The guided missile cruiser Varyag, the Pacific Fleet’s flagship, also participated, together with the Omsk nuclear-powered submarine, according to the fleet.

The exercise simulated an attack on enemy vessels. All intended targets were hit at a range of at least 300 km, the fleet said.

Japan disputes Russian sovereignty over the islands having historically owned the islands. The group includes Etorofu, Kunashiri, Shikotan and the Habomai islet group.

Japan says the islands were illegally seized by the Soviet Union shortly after Japan surrendered in the Second World War on August 15, 1945.

Russia maintains that the seizure was legitimate and that the islands became part of its territory as a result of the war.

The territorial dispute has long complicated relations between Tokyo and Moscow. Tensions have increased sharply since Russia launched its full-scale invasion of Ukraine in 2022.

Japan, along with its Group of Seven partners, subsequently imposed sanctions on Moscow.

The latest missile test adds a military dimension to an already strained diplomatic dispute. Russia’s announcement followed the Japanese protest over Putin’s visit to Etorofu and the subsequent summoning of Ambassador Muto by the Russian Foreign Ministry.

The Bastion system is based on a coastal surface-to-ship missile capability. Its deployment on Etorofu gives Russia a military presence on one of the islands at the centre of the long-running dispute.

The participation of the Varyag and Omsk also highlighted the Pacific Fleet’s role in the exercise.