Elon Musk backs call for global ban on killer robots

"Lethal autonomous weapons threaten to become the third revolution in warfare. Once developed, they will permit armed conflict to be fought at a scale greater than ever, and at timescales faster than humans can comprehend," the experts warn in an open letter released Monday.

More than a dozen countries -- including the United States, China, Israel, South Korea, Russia and Britain -- are currently developing autonomous weapons systems, according to Human Rights Watch.