> "Once they are launched, they cannot be recalled,” former Defense Secretary William Perry warns.<p>Maybe we could start by doing something about that? Obviously there would be a danger that the enemy might learn the secret codes for initiating the harmless-self-destruct sequence, and having such a system would only buy the president maybe an extra 30 minutes to discover they had made a mistake, before the enemy retaliated for real, but a cost-benefit analysis seems to support adding a Ctrl-Z keystroke to the "Destroy civilization" tool.