TOKYO (Sputnik) — The sub was detected on Monday by Japanese Self-Defense Forces patrolling waters between Japan and the Korean Peninsula, the ministry said in a statement.
"On the morning of February 15, a P-3C aircraft, a patrol helicopter and the Asagiri destroyer of the Self-Defense Forces detected a submarine in the adjacent body of water southeast of Tsushima (Nagasaki Prefecture) that was travelling from the Sea of Japan to the East China Sea," the statement read.
The adjacent body of water refers to a 12-mile stretch between Japan’s territorial waters and its special economic zone. It is not closed to navigation by foreign submarines under international laws, although this is the first time that Tokyo reports on an incident near Tsushima.
The Japanese military reported submarines passing close to its territorial waters in the southern Okinawa Prefecture three times between 2013 and 2014. The new sighting comes amid escalating tensions between Japan and China over East China Sea islands.