American intelligence officials are increasingly convinced that Iran was the origin of a serious wave of network attacks that crippled computers across the Saudi oil industry and breached financial institutions in the United States, episodes that contributed to a warning last week from defense secretary Leon Panetta that the US was at risk of a "cyber-Pearl Harbor."
After Panetta's remarks on Thursday night, American officials described an emerging shadow war of attacks and counterattacks already under way between the US and Iran in cyberspace. Among American officials, suspicion has focused on the "cybercorps" that Iran's military created in 2011.
The attack under closest scrutiny hit Saudi Aramco, the world's largest oil firm, in August.
The revelation that Iran may have been the source of the computer attacks was reported earlier by The Washington Post and The Associated Press.
Iran has a motive, to retaliate for both the American-led financial sanctions that have cut its oil exports nearly in half, and for the cybercampaign by the United States and Israel against Iran's nuclear enrichment complex at Natanz.