I'm a pacifist, so why don't I support the Campaign to Stop Killer Robots?

The Campaign to Stop Killer Robots has called on the UN to ban the development and use of autonomous weapons: those that can identify, track and attack targets without meaningful human oversight. On Monday, the group released a sensationalist video, supported by some prominent artificial intelligence researchers, depicting a dystopian future in which such machines run wild. I am gratified that my colleagues are volunteering their efforts to ensure beneficial uses of artificial intelligence (AI) technology. But I am unconvinced of the effectiveness of the campaign beyond a symbolic gesture. Even though I identify myself strongly as a pacifist, I have reservations about signing up to the proposed ban.