In the fall of 2010, Iranian officials admitted Stuxnet had infected tens of thousands of the country's computers, including some at important nuclear facilities.
Two months later, Iran's President Mahmoud Ahmadinejad, conceded that Stuxnet had "succeeded in creating problems for a limited number of our centrifuges."
Western analysts, however, have said that they believe Stuxnet had seriously set back Iran's uranium enrichment efforts by destroying or damaging hundreds of centrifuges.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is firstname.lastname@example.org.
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