For the first time, the Russian coastal defence missile systems have been dispatched near Pacific islands also claimed by Japan.
Russia moved the Bastion mobile defence system to Matua, a deserted volcanic island in the middle of the Kuril Island chain. Japan claims four of the southernmost islands.
Matua is an inhabited landmass near the centre of the Kuril Islands.
After World War II, the Soviet Union took control of the islands. Earlier, it was the home of a large Japanese base. It is now the focus of Russian efforts to boost military presence in the Pacific.