Although it's widely believed that the US and Israel were behind a Stuxnet cyber attack, there hasn't been enough solid evidence to confirm the two countries involvement. The New York times has published an in-depth report on an initiative it says is code-named "Olympic Games," spearheaded by the US government under the Bush administration and designed to attack Iranian uranium enrichment facilities. Stuxnet targeted Siemens industrial equipment to spin hundreds of centrifuges beyond their breaking points and ultimately cripple Iran's nuclear efforts.
"Should we shut this thing down?"
President Obama reportedly decided to accelerate attacks on Iran's nuclear facilities, but at one point he was concerned the worm should be stopped. "Should we shut this thing down?" he asked members of the president's national security team, after the worm escaped in the summer of 2010. Obama was informed the attacks were successful and he ordered that they should continue, temporarily disabling 1,000 of Iran's 5,000 centrifuges. Based on 18 months of interviews with current and former American, European, and Israeli officials involved in "Olympic Games," The New York Times also provides an insight into the history of the program and the rigorous collaboration with Israel.
Despite the cyberattack on Iran, Obama has reportedly warned against using cyber weapons to target additional countries, with intelligence officials revealing that the US has considered a lot more attacks than those that have taken place. A recent discovery of a "Flame" cyber worm is not thought to be part of "Olympic Games," according to the NYT. The overall risk of such weapons, especially once their source code is available, is that they can be used against the US to target key infrastructure — something that Obama would clearly like to avoid.