Three Russian naval vessels passed between Japan's two westernmost islands of Yonaguni and Iriomote, the Defense Ministry said Saturday, as tensions between Tokyo and Moscow continue to intensify over the Ukraine crisis.
The destroyer, frigate and supply ships sailed between the islands near Taiwan from Friday through Saturday and moved into the East China Sea, said the ministry, which, for the first time, disclosed Russia's naval passage in the area.
The ministry, which is analyzing the ships' actions and motives, presumed that they were on their way to return to Russia. The passage came amid an increased Russian and Chinese naval presence in waters around Japan.
Defense Minister Nobuo Kishi said last month that five Russian naval ships "almost encircled Japan," and three Chinese vessels followed a similar path.
The Russian destroyer and frigate had accompanied those five warships for part of their journey, sailing with them southward off Hokkaido and passing the Izu Islands south of Tokyo on June 16.
Intensified Russian military activity near Japan has also involved a joint flight of bombers with China over the Sea of Japan, the East China Sea and the Pacific in late May.