According to a report by Yahoo News, the mole was an Iranian engineer recruited by the Dutch intelligence agency AIVD at the behest of the CIA and the Mossad, who provided critical data that helped the US developers target their cyberattack code to the systems at Natantz.
The mole either inserted a USB flash drive with the virus onto Iranian systems, as none of the systems were connected to the internet, or manipulated another person into doing so. The Stuxnet virus ruined around 2,000 Iranian centrifuges, delaying its uranium enrichment plans by as many as a couple of years, according to analysts. Various reports suggested that the Stuxnet virus had been developed by US and Israeli intelligence services to sabotage Iran's nuclear programme. No country, however, has taken responsibility, neither for creating the virus nor for carrying out the attack.
The report cited four intelligence sources who said that the Netherlands and Germany also played a role in the development of the plan along with the US and Israel. Another country believed to be involved is France, while UK intelligence also allegedly played a role. It has been previously reported that Germany contributed technical specifications and knowledge about the industrial control systems made by the German firm Siemens, which were used in the Iranian plant to control the spinning centrifuges. The report said that France is believed to have provided similar intelligence.
The Dutch mole, according to the report, was in a unique position to deliver key intelligence about Iran’s activities to procure equipment from Europe for its nuclear program and about the centrifuges themselves, as the centrifuges at Natantz were based on designs that were reportedly stolen from a Dutch company in the 1970s by Pakistani scientist Abdul Qadeer Khan, who used them for Pakistan’s nuclear program.
Later rounds of cyberattacks on Iran's nuclear program did not require the operative's physical presence in Natantz, but his initial intelligence and physical presence provided the basis for Stuxnet's success. However, an important consequence of the Dutch operative eventually losing access to Natantz was that it may have been a factor that led the Mossad, against US advice, to reportedly act more aggressively with the Stuxnet virus in later stages.
It remains unclear why the information about the mole was made public now. Months after Stuxnet’s discovery, a website in Israel indicated that Iran had arrested and possibly executed several workers at Natantz under the belief that they helped get the malware onto systems at the plant. Two of the intelligence sources who spoke with Yahoo News indicated that there indeed had been loss of life over the Stuxnet program, but didn’t say whether this included the Dutch mole.
Neither the Mossad, nor former Mossad agents or US intelligence agents reportedly involved in operations regarding Iran at the time, have confirmed the existence of the Dutch mole so far.