U.S. authorities believe that Iranian-based hackers were responsible for cyberattacks that devastated Persian Gulf oil and gas companies, a former U.S. government official said. Just hours later, Defense Secretary Leon Panetta said the cyberthreat from Iran has grown, and he declared that the Pentagon is prepared to take action if America is threatened by a computer-based assault.

The former official, who is familiar with the investigation, said U.S. authorities believe the cyberattacks were likely supported by the Tehran government and came in retaliation for the latest round of American sanctions against Iran.