Unknown Submarine Spotted in Bungo Strait

The Japanese destroyer JMSDF Atago (DDG 177) spotted a periscope over the weekend, and with active sonar found itself a submarine. What is very interesting is where the submarine was spotted.

The submarine was detected at 6:56 a.m. south of the Bungo Strait, 7 km inside the territorial sea line and some 60 km southwest of Cape Ashizuri in Kochi Prefecture.

The nationality of the submarine was unknown, but the defense officials said it likely did not belong to the United States, Japan's closest security ally.

"It was very regrettable," Defense Minister Yoshimasa Hayashi said. "We need to do our utmost tracking down the submarine and getting to the bottom of the incident."

Hayashi suggested he did not consider the incident serious enough to order the Maritime Self-Defense Force to take maritime security operations, an operation the MSDF has taken only twice in the postwar era.

The article rules out a US Navy submarine, which only leaves 4 possible options: South Korea, North Korea, Russia, or China. It will be interesting if the media keeps asking who the submarine belongs to. If it was the port of Long Beach, the US media would keep asking until an answer was given.

We all know which country the submarine belongs to, but the question is which submarine class was able to get so close undetected?