Experts dissecting the computer worm suspected of being aimed at Iran's nuclear program have determined that it was precisely calibrated in a way that could send nuclear centrifuges wildly out of control. The paternity of the worm is still in dispute, but in recent weeks officials from Israel have broken into wide smiles when asked whether Israel was behind the attack, or knew who was. American officials have suggested it originated abroad. Computer analysts say Stuxnet does its damage by making quick changes in the rotational speed of motors, shifting them rapidly up and down. (...) Those fluctuations, nuclear analysts said in response to the report, are a recipe for disaster among the thousands of centrifuges spinning in Iran to enrich uranium, which can fuel reactors or bombs. Rapid changes can cause them to blow apart.
