"An AI set up to do the same job could also have such a scenario built in."
Which nicely sums up where AI is at the moment - there's still no "intelligence" that can realistically consider situations like this, in the way a human can, outside of its programming. What if someone had even thought about this in advance and added a rule like "do not launch counter-attack if missiles <= 5". What then if 6 "missiles" had been detected? Until such time as AIs can really play a hundred games of tic-tac-toe and come to the conclusion that "the only winning move is not to play", then it's just not safe enough to work in this sort of application.
Biting the hand that feeds IT
