Russia's fleet is launching a ten-day exercise in the sea off the country's eastern end.
40 different ships and submarines, as well as around 20 aircraft, will participate in the exercise, which will be held in parts of the Pacific Ocean, the Sea of Okhotsk, and the Sea of Japan, according to the Defence Ministry in Moscow.
The Sea of Japan is surrounded to the east and south by Japan and to the west and north by the Korean Peninsula and Russia's Far East. Russia's Pacific Fleet has its main base in the city of Vladivostok, which is located near the country's small border with North Korea.
The exercise is taking place at the same time as the Russian President Vladimir Putin is visiting North Korea.