December 19, 2007: Japanese Defense Ministry officials have revealed the kind of information contained in the CDs (of data on U.S. Aegis air defense systems) that Japanese officers had been passing around in navy schools. The information had formerly just been described as "highly classified." But the recent arrest of the officer who started it all in 2000 (by making the CD), raised questions of just how dangerous the leak was. Apparently quite serious. The CD contained considerable data on how the Aegis operated, and that provided a potential opponents with useful tips on how to defeat the system. Aegis is a warship anti-aircraft radar, one of the most advanced in the world. The CD revealed exactly how the system operates, including how quickly anti-aircraft missiles can be fired and what limitations the system has. This is all highly classified, for obvious reasons. As far as anyone knows, these CDs were not passed on to any foreign government. But the Japanese are not sure. They think they have tracked down all copies, but there's still a possibility that additional copies were made, and have been lost track of. The investigation has been under way for about a year now, and has caused the U.S. to hold back on the sale of additional high-tech systems to Japan.