Defense Minister Itsunori Onodera said Monday the Japanese government has identified which country a submarine spotted the previous day near Okinawa Prefecture belongs to and will call on it to exercise self-restraint.
Onodera did not disclose the country, saying the vessel did not intrude into Japanese territorial waters, but a government source said Sunday that it is suspected of belonging to the Chinese navy.
"We will convey to them that we are fully aware (which country the submarine is from) and urge restraint," the defense minister said. "We need to share information among Japan, the United States and South Korea."
The unidentified submarine was spotted by a P-3C patrol aircraft of the Maritime Self-Defense Force early Sunday in Japan's contiguous zone south of Minamidaito Island in Okinawa Prefecture but it did not enter Japanese waters, according to the Defense Ministry.
Sailing in Japan's contiguous zone, an area outside territorial waters where Japanese law may be applied, poses no problem in terms of international law.