Investigators in Japan looking into the leak of data relating to the Aegis missile defense system have discovered other sensitive US military information has been leaked, Japan's Kyodo News reported on Tuesday.
The additional data includes "the highest level of information" relating to sea-based Standard Missile-3 interceptors and the Link 16 system, which is used to exchange reconnaissance satellite data between Japan and the US, Kyodo said, quoting "informed sources."
The revelation that additional information has fallen into the hands of those that shouldn't have it will likely cause further embarrassment for Japan and could affect the deployment of US military hardware in the country and Japan's plans to buy F-22A Raptor fighter jets. Japan is currently asking the US to supply confidential information relating to the jets.
The Aegis leak first came to light in March when police were searching the home of a Japan Maritime Self Defense Force (JMSDF) officer as part of an immigration investigation of the officer's wife, who is Chinese. The officer wasn't supposed to have the data in question, including an educational document that concerned the radar and transmission frequencies of the Aegis system, triggering the investigation.
The officer said he accidentally copied the file while swapping pornography with another JMSDF officer, according to a report in the Yomiuri Shimbun newspaper. Its source was traced back to a senior grade lieutenant who in turn said he obtained the file from a lieutenant commander, according to previously published reports. The commander denied the claim.
On Saturday police raided a navy school in Hiroshima as part of the investigation and confiscated personal computers and storage devices.
To date there hasn't been any suggestion that the information leaked beyond the JMSDF, however the investigation is not over. As the defense systems in question are in use by the US military, a wider leak would affect the US and other allies.
The US cooperates closely with Japan on defense matters as part of the Japan-US Mutual Defense Assistance Agreement, which calls on the two countries to cooperate with each other in maintaining and developing their respective defense capabilities.