On the evening of March 15, the Maritime Self-Defense Force detected two Russian Navy ships heading west in waters about 70 kilometers east-northeast of Shiriyazaki cape in Aomori Prefecture. The Shiranui, a destroyer from the Ominato base in the prefecture, and a P-3C patrol plane from the Hachinohe Air Base, also in Aomori Prefecture, began tracking the Russian vessels.
The Russian ships eventually passed through the Tsugaru Strait between Honshu and Hokkaido and reached the Sea of Japan. Photographs taken from the P-3C clearly showed at least 10 vehicles loaded on the deck of one vessel.
