Leon Panetta, the US Defence Secretary, has warned of a national security calamity as grave as Pearl Harbor and 9/11 if the United States does not protect critical installations such as power plants and train networks against cyber attacks.
Speaking to business leaders at a conference on board the Intrepid Sea, Air & Space Museum in New York, Mr Panetta painted a grim picture of what could happen if unfriendly foreign forces tampered with the computer systems that control the country's infrastructure. Officials said he was referring in part to Russia, China, Iran and foreign terror groups.
"They could derail passenger trains loaded with lethal chemicals," he suggested. "They could contaminate [cities'] water supplies, or shut down the power grid across large parts of the country." He added: "A cyber attack perpetrated by nation states or violent extremist groups could be as destructive as the terrorist attack of 9/11."
His comments were directed in part at Republicans in Congress who blocked attempts to impose rules on infrastructure firms, saying they would be a burden on private businesses.