The malware was designed to secretly map Iran's computer networks and monitor the computers of Iranian officials to collect intelligence used to enable an ongoing cyberwarfare campaign, Western officials with knowledge of the effort told The Washington Post.
Involving the National Security Agency, the CIA and Israel's military, the campaign included the use of the destructive Stuxnet virus to cause malfunctions in Iran's nuclear enrichment equipment, the sources told the Post.
"This is about preparing the battlefield for another type of covert action," one former high-ranking U.S. intelligence official said.
Flame and Stuxnet were elements of a broader assault that is ongoing, he said.
"Cyber collection against the Iranian program is way further down the road than this," the official said.
Word of the Flame malware came when Iran detected a series of cyberattacks on its oil industry, apparently directed by Israel in a unilateral operation that caught its U.S. partners off guard, several U.S. and Western officials said, speaking on the condition of anonymity.
The CIA, the NSA and the Office of the Director of National Intelligence, as well as the Israeli Embassy in Washington, have declined to comment, the Post said Tuesday.