The hardware and software controlling a deadly robot needs to come equipped with “safeties, anti-tamper mechanisms, and information assurance.” The design has got to have proper “human-machine interfaces and controls.” And, above all, it has to operate “consistent with commander and operator intentions and, if unable to do so, terminate engagements or seek additional human operator input before continuing the engagement.” If not, the Pentagon isn’t going to buy it or use it.

It’s reasonable to worry that advancements in robot autonomy are going to slowly push flesh-and-blood troops out of the role of deciding who to kill. To be sure, military autonomous systems aren’t nearly there yet. No Predator, for instance, can fire its Hellfire missile without a human directing it. But the military is wading its toe into murkier ethical and operational waters: The Navy’s experimental X-47B prototype will soon be able to land on an aircraft carrier with the barest of human directions. That’s still a long way from deciding on its own to release its weapons. But this is how a very deadly slope can slip