Military vessels from China and Russia passed through the narrow Tsugaru Strait located between the Japanese islands of Honshu and Hokkaido on Monday. The Tsugaru Strait separates the Sea of Japan from the Pacific.

The Japanese Defence Ministry which released the information said that the reasons for the two navies to pass through the strait are not known. At its narrowest, it is just 18.7 km.

Kyodo News reports that this is the first time that Japan has confirmed the passage of the vessels. A Defence Ministry spokesperson said: "No violation of territorial waters has taken place, and no international rule has been ignored".

Japan says the ten naval vessels sailed from the Sea of Japan to the Pacific Ocean, through the Tsugaru Strait, which is an international passage open to foreign ships, including navy ships. NHK Japan website has put up a video showing the Russian and China navy pass through waters close to Japan.

The two powers had held joint naval drills on October 14-17 in the Sea of Japan as part of military cooperation between the two countries. Some of the vessels have supposedly taken part in the drills, which saw destroyers and submarines participate in communications, mine removal and artillery firing.

Moscow and Beijing are coming together in recent years as the West sees a gradual decline. Both the countries also have a territorial conflict with Japan in the region.

With Russia, Japan has issues over the Kuril Islands which Tokyo calls as Northern Territories. The two nations have been in recent talks to resolve the issue.

Similarly, China and Japan have a dispute over the Senkaku islands, which lie close to Taiwan.

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