September23, 2008:  On September 13th, the Japanese destroyer Atago spotted a submarine periscope about a kilometers away. Even the ship's captain got a look at it before it submerged. The Atago turned on its sonar, and radioed headquarters to see if there were any American or Japanese subs in the area (off Kochi prefecture, on the southeast Pacific coast). There weren't. The sub was in Japanese waters, and according to international law, should have surfaced and identified itself when pinged by sonar. But instead, the sub sped up and moved away. The Atago did not have a helicopter on board to aid in the search, and after 90 minutes, the sub slipped away.

The sonar contact did reveal the sub to be, most likely, Russian or Chinese. The Japanese keep an eye on the choke points the Russians must use to get their subs out to the ocean, and, without giving anything away, said they did not believe the boat was Russian. That left the Chinese, who have been sending their subs farther and farther afield over the last few years. Four years ago, a Chinese nuclear powered sub was caught in Japanese waters, and the Chinese eventually apologized for that.

The U.S. has underwater surveillance systems that cover most of the Pacific, but there was no public American report on whether any subs had been spotted in that area. The U.S. is very secretive about their wade area underwater sensor system, so as not to give any potential enemies useful information on what the system can, and cannot, track.

The Atago incident caused Japanese politicians to call for a change in the current laws, so that Japanese ships can use force (depth charges, or even torpedoes) to go after subs that are illegally intruding into Japanese waters. But the most embarrassing aspect of the incident was the inability of the Japanese to track the intruder. Japanese still remember the starvation of the last year of World War II (1945), when submarines and naval mines cut off food imports and caused a deadly famine.