(They are already commonly used in reconnaissance and bomb-disposal, but their use in combat (without any human control mechanism) raises tricky questions.
The MoD argues that if a drone's control system takes appropriate account of the law on armed conflicts (basically military necessity, humanity, proportionality and the ability to distinguish between military targets and civilians), then an autonomous strike could meet legal norms.)
What a shame they haven't read the 3 laws of robotics:-