Security experts warn that the United States faces the real danger of a massive attack by foreign cyber terrorists.
They say intruders have already infiltrated critical U.S. systems and could launch what they call a cyber "Pearl Harbor" attack.
U.S. Secretary of Defense Leon Panetta said electronic attacks on our country's critical infrastructures are becoming more damaging and perilous.
In recent weeks, attackers have struck major financial institutions in the United States and several oil facilities in the the Middle East.
"These attacks mark a significant escalation of the cyber threat," Panetta said. "And they have renewed concerns about still more destructive scenarios that could unfold."
Panetta's biggest worry: that a "one-two punch" involving multiple strikes on vital sectors like utility plants, transportation systems, or financial networks, combined with a physical attack on the country could result in a cyber "Pearl Harbor."
"The cyber attack perpetrated by nation states or violent extremist groups could be as destructive as the terrorist attack on 9/11," Panetta said.
The Pentagon is particularly concerned about cyber threats from Iran, China, and Russia. While not mentioning specific countries, he said foreign actors have already probed our country's key infrastructures.
"We know of specific instances where intruders have successfully gained access to these control systems. We also know they are seeking to create advanced tools to attack these systems and cause panic, destruction, and even the loss of life," Panetta warned.
The Department of Defense is spending more than $3 billion a year in cyber security. But Panetta wants to do more. He's pushing Congress for legislation that would require new standards at critical private-sector infrastructure facilities.
Some have blocked his efforts, however, because new regulations would be burdensome for business.