I know you said random, but I gotta call you on this.... 50%??? You think they'd let the risk factor get that high before they acted?? A 1-in-2 chance of Cali being wiped off the map before US forces started "shifting East"? The US government (at least under George W Bush) had a One Percent Doctrine. Basically if a threat exceeded a one percent chance of happening (such as the threat of Pakistan nuke scientists selling secrets to Al Qaeda... or Iraq possibly having WMDs) they acted as if the 1% chance were a certainty. If Cali had a higher than 1% chance of being nuked there would be a diplomatic stand-off (ala Cuban Missile Crisis) or some kind of military action.