"My opinion is that Mossad is involved," he said. "There is only one leading source, and that is the United States."
Symantec had suggested in a report on Stuxnet that it would have taken a team of between 5 and 10 developers about six months to create the Stuxnet worm. Langner says they needed to have inside information to get the worm to its intended targets and to carry out its duties.
Analysts say that Stuxnet was likely designed to damage centrifuges used in the process of enriching uranium. The worm targeted programmable logic controllers (PLCs) made by Siemens, which are used to control a wide variety of industrial systems.
Iran's Interior Ministry denied earlier this week that Stuxnet was responsible for a shutdown at the Bushehr nuclear reactor. Despite the thorough analysis done of Stuxnet itself, there is no hard evidence to link either the United States or Israel to its development.