https://en.wikipedia.org/wiki/Operation_Olympic_Games#Histor...
> A programming error later caused the worm to spread to computers outside of Natanz. When an engineer "left Natanz and connected [his] computer to the Internet, the American- and Israeli-made bug failed to recognize that its environment had changed." The code replicated on the Internet and was subsequently exposed for public dissemination. IT security firms Symantec and Kaspersky Lab have since examined Stuxnet. It is unclear whether the United States or Israel introduced the programming error.
Also bearing mention is Flame, which is often left out when Stuxnet comes up, but which was allegedly part of the wider operation.
https://en.wikipedia.org/wiki/Operation_Olympic_Games#Signif...
> The Washington Post reported that Flame malware was also part of Olympic Games.
https://www.washingtonpost.com/world/national-security/us-is... | https://web.archive.org/web/20220322045917/https://www.washi... | https://archive.is/6hRl7
> “We are now 100 percent sure that the Stuxnet and Flame groups worked together,” said Roel Schouwenberg, a Boston-based senior researcher with Kaspersky Lab.
> The firm also determined that the Flame malware predates Stuxnet. “It looks like the Flame platform was used as a kickstarter of sorts to get the Stuxnet project going,” Schouwenberg said.