That's the warning contained in a new report from Pax, a nonprofit based in the Netherlands that campaigns for peace around the world.

Killer robots, or lethal autonomous weapons systems, are designed to make life-or-death decisions on their own, without human control. It's a worrying leap that's been called the "third revolution in warfare," after gunpowder and the atomic bomb. Both activists and military leaders have called for international regulations to govern these weapons, or even ban them outright, but key governments—like the United States and Russia—have so far resisted.

As far as anyone knows, militaries have yet to actually deploy killer robots on the battlefield, at least offensively. But Pax has identified at least 30 global arms manufacturers that don't have policies against developing these kinds of weapons systems, and are reportedly doing so at a rate that is outpacing regulation.