from a piece in "The American Conservative': (print edition only, no link)
The Pentagon, acting under instructions from Vice President Dick Cheney's office, has tasked the United States Strategic Command (STRATCOM) with drawing up a contingency plan to be employed in response to another 9/11-type terrorist attack on the United States. The plan includes a large-scale air assault on Iran employing both conventional and tactical nuclear weapons. Within Iran there are more than 450 major strategic targets, including numerous suspected nuclear-weapons-program development sites. Many of the targets are hardened or are deep underground and could not be taken out by conventional weapons, hence the nuclear option. As in the case of Iraq, the response is not conditional on Iran actually being involved in the act of terrorism directed against the United States. Several senior Air Force officers involved in the planning are reportedly appalled at the implications of what they are doing--that Iran is being set up for an unprovoked nuclear attack--but no one is prepared to damage his career by posing any objections.
http://www.justinlogan.com/justinlogancom/2005/07/what_is_the_pla.html