Toby Walsh is an Australian professor of computer science working to prevent the development of autonomous robotic weapons:
[Y]ou can’t have machines deciding whether humans live or die. It crosses new territory. Machines don’t have our moral compass, our compassion and our emotions. Machines are not moral beings.
The technical argument is that these are potentially weapons of mass destruction, and the international community has thus far banned all other weapons of mass destruction.
Toby Walsh, A.I. Expert, Is Racing to Stop the Killer Robots
Different emphasis, but again the focus is on human-in-the-loop safety.