War has been a driver of breakthrough technology for a long time. The first waves of artificial intelligence and even the internet came out of DARPA, a defense agency whose original mission was to keep the U.S. technologically ahead of the Soviet Union. But what happens when the battlefield is increasingly dominated by autonomous weapons, which don't require humans in the loop to shoot and kill? In this episode: Arati Prabhakar, former head of DARPA; Richard Danzig, former Navy Secretary; Paul Scharre, author of "Army of None"; and Jonathan Wilson, former Navy SEAL.