The Department of Defense reported that it's computer networks were subject to 14,500 break in attempts by hackers last year. Only 70 of those attempts succeeded, and only three caused any damage. More worrisome are the break ins that are not detected. The most skillful hackers approach a break in as a major operation, taking weeks or months to scout the target system. Once the target is thoroughly known, the hackers enter undetected, do what they came to do, and then leave, with no trace of their work left behind. The Department of Defense did not report on how they are dealing with these industrial strength attacks. And that's because the less the ace hacker knows the harder it is to pull off a stealth penetration. There have been stealth penetrations in the past, which were eventually discovered. Much of the Department of Defense work on computer network defenses is highly classified.