Asimov covered all that

Seems there's a long (117 pages) and typically tediously titled academic paper called Governing Lethal Behavior: Embedding Ethics in a Hybrid Deliberative/Reactive Robot Architecture, on the "ethical implications of robots in war".
For those of us who remember, this has been already dealt with (in 1942, before there really were robots), and far more succinctly, in Asimov's three Laws of Robotics:

First Law: A robot may not injure a human being or, through inaction, allow a human being to come to harm.
Second Law: A robot must obey orders given to it by human beings, except where such orders would conflict with the First Law.
Third Law: A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

He later added the Zeroth Law: A robot may not harm humanity, or, by inaction, allow humanity to come to harm.

Rico says that pretty much (and wisely) precludes the use of autonomous robots in warfare; if anyone's seen the Terminator movies, that's why...