report said that 1,000 to 2,000 centrifuges were removed from natanz for unknown reasons.targets 1,000 centrifuges. so from that, people are drawn to the conclusion, well, stuxnet got in and succeeded. that's the only evidence that we have. >> kroft: the only information that's not classified? >> Ó murchú: yes. >> kroft: and there are lots of things about stuxnet that are still top secret. who was behind it? >> Ó murchú: what we do know is that this was a very large operation. you're really looking at a government agency from some country who is politically motivated, and who has the insider information from a uranium-enrichment facility that would facilitate building a threat like this. >> kroft: an intelligence agency, probably? >> Ó murchú: probably. >> langner: we know from reverse engineering the attack codes that the attackers have full-- and i mean this literally-- full tactical knowledge of every damn detail of this plant. so you could say, in a way, they know the plant better than the iranian operator. >> kroft: we wanted to know what retired general michael hayde