A group of the world's top technology leaders have published an open letter urging the UN to ban the use of artificial intelligence in weapons systems, amid growing concerns that autonomous killer robots could wind up taking control. The group of 116 companies, most of which specialize in robotics or AI, argued that its growing use could revolutionize modern warfare in irreversible ways and pose a danger to nation states. "Lethal autonomous weapons threaten to become the third revolution in warfare," the letter states.