Cyber attacks pose the greatest threat to the United States after nuclear war and weapons of mass destruction – and they are increasingly hard to prevent, FBI experts say. “Other than a nuclear device or some other type of destructive weapon, the threat to our infrastructure, the threat to our intelligence, the threat to our computer network is the most critical threat we face,” he added. US experts warn of “cybergeddon”, in which an advanced economy – where almost everything of importance is linked to or controlled by computers – falls prey to hackers, with catastrophic results.