I'm afraid history has shown that once the cat is out of the bag someone will use it and other countries will follow suit. And the cats already out of the bag because the technology that allows autonomous cars, civil/industrial robots, drones, and face recognition programs to work just need to be combined and modified to make "killer robots".
An argument against would be that something like a killer drone with face recognition could take out terrorist leaders with less collateral damage than the usual bombs / missiles.