The U.S. Secretary of Defense said Monday night that Iran will not be allowed to develop a nuclear weapon. In an interview, Leon Panetta, said despite the efforts to disrupt the Iranian nuclear program, the Iranians have reached a point where they can assemble a bomb in a year or potentially less.

Secretary Panetta spoke with us at the end of an overseas trip during which he reviewed strategy in Afghanistan and formally ended the war in Iraq.

CBS News anchor Scott Pelley caught up with Secretary Panetta on his tour last week of Iraq, Afghanistan and Libya. On the way home, he boarded the jet nicknamed "The Doomsday Plane." This is the command post where he and the president would direct a nuclear war. In an interview for "60 Minutes," we sat down in the compartment where he would execute the commander-in-chief's orders. Panetta told CBS News that Iran needs only one year to build a nuclear weapon.

Pelley: So are you saying that Iran can have a nuclear weapon in 2012?

Panetta: It would probably be about a year before they can do it. Perhaps a little less. But one proviso, Scott, is if they have a hidden facility somewhere in Iran that may be enriching fuel.

Pelley: So that they can develop a weapon even more quickly...

Panetta: On a faster track....

Pelley: Than we believe....

Panetta: That's correct.