The Japanese government scrambled on Friday to find out how video of an altercation between a Chinese fishing trawler and the Japan Coast Guard ended up on YouTube. Its appearance marked the second time this week that sensitive government information was leaked on to the Internet.
Several video clips posted to YouTube show a Sept. 7 incident that occurred near a disputed island chain and resulted in the captain of a Chinese fishing boat being arrested.
In the most dramatic of the clips, a coast guard vessel is sailing alongside the fishing boat, blaring its siren and shouting in English and Chinese for the fishing boat to stop. The two ships then collide. In another clip the Chinese boat collides side-on with a coast guard vessel.
Japan and China regularly argue over the islands, but the disputes are usually small in scale. This time, with the arrest of the Chinese captain, things escalated and prompted protests in both countries.
Relations between the two countries were just beginning to improve after the incident at sea, with a meeting planned on the sidelines of an economic summit in Japan next week. The appearance of the video online threatened to put back these bilateral efforts, but the Chinese government appears to have taken the video in its stride and has been removing copies of the video from domestic video sites.
In Japan the footage played all day on television news and has embarrassed the government. The pressure is now on to find the source of the leak and the Coast Guard Agency said it would work through the weekend to do that.
"We're conducting a thorough investigation," Japan Coast Guard chief Hisayasu Suzuki told a Friday evening news conference.
There appear to be two possible sources for the leak.
The first and most likely is from within the government. Several agencies have been involved in the case and the video was copied onto at least ten DVDs for distribution, according to local media reports.
The second is that it was intercepted when sent via satellite from the ship to Tokyo, but this would require special equipment: It was sent as a data file, not a TV video feed. If it was encrypted -- something that isn't known at present -- it would be even more difficult to pull out of the sky.
Several government officials said a criminal case could be brought against the person who leaked the footage, depending on the results of the investigation.
The YouTube account that hosted the video has been deleted and offered no clues as to the identity of the person behind the account. The account was created on Thursday and the first video was uploaded at around 9pm local time. A Twitter account of the same name with links to the same videos was also created. The three Twitter messages were posted late Thursday, around the same time the videos appeared online.
The leak comes days after a cache of police documents was discovered on a Japanese file-sharing network.
The documents, which were posted to the Winny network, reportedly included some relating to international terrorism.
Winny is a popular file-sharing application in Japan, but it contains a number of bugs that allow for the user's computer to be attacked. There have been many previous cases of confidential government or corporate documents appearing online because of the careless use of Winny on work computers and the same had been feared this time.
Japanese media reported on Thursday that the leak appeared to have been deliberate.
(Additional reporting by Michael Kan in Beijing.)
Martyn Williams covers Japan and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com