Microsoft chief Brad Smith issued a warning over the weekend that killer robots are ‘unstoppable’ and a new digital Geneva Convention is required.

Most sci-fi fans will think of Terminator when they hear of killer robots. In the classic film series, a rogue military AI called Skynet gained self-awareness after spreading to millions of servers around the world. Concluding that humans would attempt to shut it down, Skynet sought to exterminate all of mankind in the interest of...