Not a bomb...a computer system capable of nuclear counterstrike. But while it does have a nuclear arsenal at its disposal, it supposedly cannot be activated without at least some form of human confirmation. But it only takes one crazy, paranoid person to set things in motion if it comes to that point.
But yeah, the end result would be omfg-we're-all-dead. Or at least most of us, especially if you're living in the U.S. (which is probably where most of the missiles are aimed).