This is indeed a major problem. The number of activities we undertake on NIPRNET is shocking, and forget about the incidental activities of individuals–this is official activity (which of course I won’t detail).
“The problem is huge and more dangerous than anyone initially believed. The basic problem is that the U.S. military embraced the Internet early and has by now become one of the heaviest users on the planet. With millions of users, over a million devices connected to the Internet, and over 10,000 separate networks, the Department of Defense is also one of the most difficult Internet targets to defend. With so much exposure, and not enough money to install (and manage) adequate security, the Department of Defense has been searching for the most efficient strategy to deal with expected Chinese attacks.
This has led to studies of what kind of damage the Chinese could do and how best to cope with it. This sort of thing involves finding out what operations could be shut down (and for how long) and what impact this would have on military operations. The most vulnerable operations involve logistics. This covers everything from handling requests for spare parts, ammo, and fuel as well as requests for specialized maintenance services and control of aircraft and ships moving supplies.”