and langner speculated publicly that stuxnet was out to sabotage iran's nuclear program. >> langner:e that the highest number of infections had been reported in iran. and second, it was pretty clear, just by looking at the sophistication, that there would be at least one nation-state behind this. you know, you just add one and one together. >> kroft: by the fall of 2010, the consensus was that iran's top-secret uranium enrichment plant at natanz was the target, and that stuxnet was a carefully constructed weapon designed to be carried into the plant on a corrupted laptop or thumb drive, then infect the system, disguise its presence, move through the network, changing computer code and subtly alter the speed of the centrifuges without the iranians ever noticing-- sabotage by software. >> oÓ murchú: stuxnet's entire purpose is to control centrifuges-- to make centrifuges speed up past what they're meant to spin at and to damage them. certainly, it would damage the uranium enrichment facility, and they would need to be replaced. >> kroft: if the centrifuges were spinning too fast, would