The Chinese and Russian navies kicked off the second stage of the Joint Sea 2017 drills on Monday, which also marked the 86th anniversary of Japan's invasion of Northeast China.

The weeklong exercise will be held in the Sea of Japan and, for the first time, in the Sea of Okhotsk, north of Japan's Hokkaido Island, according to Vladimir Matveev, spokesman for Russia's Pacific Fleet, who was quoted by Russian Times.

It is also the first time the two navies have conducted joint submarine rescues and antisubmarine exercises involving multiple types of aircraft, vessels and military personnel.