The Law of the Sea treaty is a nice example, she said, "but to copy this for cyberspace is not easy."
There are other boundaries to set when it comes to drone warfare, too.
"We have fully autonomous defensive weapons today," Cummings said. She wondered why they are OK, while fully autonomous offensive weapons are not.
She raised the question of future autonomous missile technology that might be able to target a person not by their GPS coordinates, as today, but by their photograph. "That missile could do a better job of targeting a bad person than a human could," she said. That scenario would make her reluctant to put a blanket ban on autonomous offensive weapons, she said.
Targeting a specific person through their photo "really is an illustration of the blurring of the line between war and peace," said Jean-Marie Guéhenno, president and CEO of International Crisis Group and a former UN peacekeeper. The traditional way of dealing with that would be through a court or military tribunal, he said.
Airborne drones aren't the only autonomous vehicles that might cause concern, Cummings said.
"When we go to an internet of things for vehicles, we will have a potential worldwide connectivity of terrorism, where terrorists can get into the network and start hacking driverless cars."
Worse still, she said, they could hack a truck. They don't even have to have explosives on board to cause trouble she said: Hacking half a dozen trucks in the Washington, D.C., area and stopping them in the right places could bring traffic to a halt and open the way for all sorts of mischief.
But what of social media? "Does the power of social media mean traditional military might is less important?" asked Shirley Ann Jackson, president of Rensselaer Polytechnic Institute.
Social media plays a role, said Lawrence Freedman, emeritus professor of war studies at King's College London. "But I don't think we should consider that new," he said. "If we look back at the strategists of the past, what they called the psychological element was always there, was always important."
So there you have it: In the future, war may not be declared by drones dropping destruction on our heads, but by a spate of unexplained illegal parking downtown.
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