I had to chuckle a little when I saw this story. This is supposed to be a closed network with no outside access. The presumption is that external drives probably caused the virus. Of course many other theories I am sure could be conceived (with tinfoil hat firmly in place) like China installed them on the drives, the DOD actually put them there on purpose to monitor pilots and others and the AV accidentally picked it up, etc.
In any case, its funny to consider, I figure its likely just incompetence and running a Windows based OS that is probably not patched to current levels since they are on a “closed” network with no Internet. Like we try to teach folks – dont let technology remove your common sense. You the user still have to practice safe computing. There was likely some update done to the removable drive software, and that did it. I also think its funny they say….”yeah it just keeps coming back”. Um OK even after a clean reinstall. Ok good…I am glad nobody is overly concerned yet. I still want to read those emails to Mom. 
