During the first two days of June, an Internet based virus appears to have got into the U.S. Air Force networks at the Royal Air Force base at Lakenheath. This is the largest U.S. Air Force operation in the United Kingdom. The air force would not provide any information on what had caused the many "computer problems" on the base, but it was known that they were network, and Internet, related. This is not the first time this sort of thing has happened. The U.S. Department of Defense has over a million PCs, and thousands of networks. Security has always been a problem, as has training for users. In the past, the Department of Defense is known to have been hit at least as hard as most major corporations, when a particularly nasty bug got loose on the web. And there have been some real horror stories. Some are still classified, although on some others, the details eventually got out. The problems almost always get traced back to problems with not having enough well trained personnel to implement all the proper software, patches and procedures, to protect a particular bunch of networks (usually those on a particular base or facility).
What apparently happened at Lakenheath (a virus or worm that gummed up the network, or partially destroyed files on a lot of hard drives), is an example of what one can expect if Cyber War is used in wartime, or by terrorists. The basic tactic for Cyber War is to find a new Internet vulnerability, and then develop a virus or worm that will exploit it, and keep it in your arsenal until there's a war or, more commonly the vulnerability gets patched.
Welcome to the future.