A mysterious submarine that briefly entered Japanese territorial waters earlier this week without identifying itself came from China, Japan's top government spokesman said yesterday.
Japan's navy has been on alert since Wednesday, when the submarine was first spotted off the nation's southern island of Okinawa.
Tokyo had sent reconnaissance aircraft and naval destroyers to shadow the submarine, which had spent about two hours inside Japanese waters before heading north.
Chief Cabinet Secretary Hiroyuki Hosoda said Tokyo had concluded that it was a Chinese nuclear submarine after considering a range of factors, including the fact that the submarine appeared to be heading toward China.
"Judging from several pieces of information, we found that the submarine belongs to the Chinese navy and we plan to lodge a protest soon through diplomatic channels," Hosoda told a news conference.
Defense Agency chief Yoshinori Ono lifted Japan's naval alert yesterday, Hosoda said.
He didn't specify whether the aircraft and destroyers were returning home or whether the submarine had surfaced.
Tokyo had previously said it couldn't identify the submarine because it remained under water. Japanese media had cited defense officials as saying it likely was a Chinese Han-class nuclear submarine, based on the noise it was making and the length of time it had stayed beneath the sea's surface.
Beijing had no immediate comment.
On Thursday, China's Foreign Ministry spokeswoman Zhang Qiyue ((
Territorial disputes have occasionally flared up between Japan and its neighbors, China and South Korea. In recent months, Tokyo has squabbled with Beijing over natural gas deposits in the East China Sea.
Japan has accused China of conducting surveys for gas fields near Okinawa that extend into Japanese territorial waters.
China says its activities are close to its coast and don't concern Japan and has rejected offering more information.
Japan has been considering ways to boost its maritime defenses after a shoot out with a suspected North Korean spy ship in December 2001.