The U.S. has recently acknowledged developing cyberweapons but to this point has not admitted using them. Suspicions were raised with the discovery of the "Stuxnet" worm in 2010. The Times reports that the worm was part of a program, begun under President George W. Bush, that aimed to disrupt the centrifuges at the Natanz nuclear facility in Iran. It was released onto the web due to a programmer’s error.
A new cyberweapon called Flame was recently discovered to have attacked Iranian computers, and while the Times says that Flame was not part of the program used against Iran, officials declined to say whether the U.S. was responsible for it.
It is not clear how effective the attacks had been. Administration officials say Iran’s efforts have been set back by 18 months to two years, but other outside experts are more skeptical.
Israel’s involvement in the attack was crucial, according to the Times. A secret Israeli unit aided the Americans in developing the worm that would attack Iran’s computers. The Times reports that the U.S. also had a second motive in employing the Israelis: to forestall a military strike against Iran’s nuclear capabilities.