Japan's Ministry of Defense announced on August 20 that the P-3C patrol aircraft of the Japan Maritime Self-Defense Force observed in the evening of August 19 four Chinese naval ships, including two destroyers and two frigates, in the Tsugaru Strait off the coast of Tappi Misaki, Aomori Prefecture. These four warships sailed from the Sea of Japan to the Pacific Ocean in the high seas area of the Tsugaru Strait.