http://news.bbc.co.uk/2/hi/in_depth/3998107.stm
There has been a military alert in Japan after an unidentified submarine was detected inside the country's territorial waters.
Surveillance aircraft spotted the submarine near the southern island of Okinawa and the Japanese navy was ordered to investigate.
Officials said the government was trying to establish the vessel's country of origin.
The submarine has already left Japanese waters, officials said.
More soon.
There has been a military alert in Japan after an unidentified submarine was detected inside the country's territorial waters.
Surveillance aircraft spotted the submarine near the southern island of Okinawa and the Japanese navy was ordered to investigate.
Officials said the government was trying to establish the vessel's country of origin.
The submarine has already left Japanese waters, officials said.
More soon.
