US intelligence officials say there is growing evidence Iran was behind recent cyber attacks that disabled computers across the Saudi oil industry.
These attacks contributed to a warning last week from Defense Secretary Leon Panetta that the US was at risk of a "cyber-Pearl Harbor,” according to the New York Times.
After Panetta's remarks on Thursday, US officials described an emerging shadow war of attacks and counterattacks already under way between the United States and Iran in cyber space, the paper said.
There is no evidence the attacks were approved by the Iranian government, but several news agencies report that US officials suspect the involvement of the Iranian military’s cyber unit. The Iranian military set up the cyber unity in 2011, and US officials suspect it of orchestrating the attack in August on rival Saudi Aramco, the Saudi state oil company.
Around 30,000 computers on Aramco’s network were infected with the Shamoon virus. The malware wiped all files on the computers by overwriting them.
Panetta said Iran had undertaken a concerted effort to use cyberspace to its advantage. Defence analysts interpreted that as meaning Iran had discovered a new way to harass much sooner than expected, and the US was ill-prepared to deal with it.
Iranian cyber retaliation for Stuxnet
According to the New York Times, Iran has a motive to retaliate for the US-led financial sanctions that have cut its oil exports nearly in half, and for the cyber campaign by the US and Israel using Stuxnet against Iran's nuclear enrichment complex at Natanz.
The US has never officially acknowledged its role in creating Stuxnet and Panetta avoided using the words "offence" or "offensive" in the context of US cyber warfare. But he did say cyber defence alone would not prevent an attack.
"If we detect an imminent threat of attack that will cause significant, physical destruction in the United States or kill American citizens, we need to have the option to take action against those who would attack us to defend this nation when directed by the president," said Panetta.
"For these kinds of scenarios, the department has developed that capability to conduct effective operations to counter threats to our national interests in cyberspace.”
The US defence department had developed tools to trace attackers, Panetta said, and a cyber-strike force that could conduct operations via computer networks. The department is also finalising changes to its rules of engagement that would define when it could confront major threats quickly.
"Potential aggressors should be aware that the United States has the capacity to locate them and hold them accountable for actions that harm America or its interests," said Panetta.