Surprise! PLA hackers have stolen weapons plans from the military.
Why does every system have to be Internet facing? I can see commerical enterprises wanting to save money but using public networks, but government and the military? For them, money is merely a way to keep score. It's not real.
Just as two can keep a secret if one of them is dead, if you want a secure system, segregate it; take it offline. While I'm pained to think of the lost information, it's even more painful to know that it could have been prevented.