Yeah, the military (ours and Britain's and probably a few others) integrated Windows XP years ago into the control and/or monitoring systems. And it's still there.
I don't have the links right at hand, but Google is your friend -- there are recurring tech articles about the compromised security that has resulted from the military using Windows in mission critical applications.
My engineer pals have several XP boxes in use. I have been told that they don’t run anything, just glorified monitoring units.