Four Russian warships passed through the Tsugaru Strait in northeastern Japan between Tuesday and Wednesday, possibly transporting troops and combat vehicles to Ukraine, Japan’s Defense Ministry said, writes CNN.

“Japan’s Ministry of Defense will continue to monitor the situation and movements of the Russian army with a high sense of caution”, - the ministry said on its official Twitter account.

The Tsugaru Strait connects the Sea of Japan with the Pacific Ocean and is located between Japan’s two largest main islands, Honshu and Hokkaido.