An Iranian engineer recruited by the Dutch intelligence agency AIVD at the behest of the United States Central Intelligence Agency and the Mossad intelligence agency provided critical data that helped the US developers of the Stuxnet virus target their code to the systems at the Natanz nuclear facility, according to to four intelligence sources who spoke with Yahoo News.
That mole then provided much-needed inside access when it came time to slip Stuxnet onto those systems using a USB flash drive.