U.S. officials have told members of Congress that the August 14 power failure in the United States and Canada has re-energized efforts aimed at making sure the electricity distribution system cannot be disrupted by terrorist activities.
The officials say that based on investigations so far, there is no evidence the power failure that affected the northeastern United States as well as Michigan and Canada, was a result of any action by international or domestic terrorist groups or other criminal activity.
The officials call these conclusions preliminary, and note that investigations by the Department of Homeland Security and various other groups are continuing.
However, Larry Mefford, executive assistant director for counterterrorism for the FBI, says this does not mean terrorist groups are not targeting the nation's power infrastructure.
"We remain very alert, however, to the possibility that terrorists may target the electrical power grid and other infrastructure facilities of our country," he said. "They are clearly aware of the importance of electrical power to the national economy and livelihood."
Mr. Mefford says al-Qaida and other terrorist organizations have clearly looked at a variety of methods to stage attacks against the United States and its interests.
Cofer Black, the U.S. State Department's coordinator for counter-terrorism says that while there has been significant progress in the war on terrorism, power failures are what he calls an "urgent reminder" of vulnerabilities that can be exploited.
"Critical infrastructure essentially means all the physical and virtual ties that bind us together, not only as a society but as a world," he said. "Terrorists know this and they see attacking the very bonds that hold us together as one more way to drive us apart."
One of the concerns lawmakers have is that terrorists, or others intending to do harm to the U.S. power infrastructure, might be able to trigger a blackout using the internet.
The officials say there is also no evidence the blackout was caused by any computer or internet-related attack on the power distribution system.
However, in response to questions neither Mr. Black nor Mr. Mefford were willing to speculate as to whether a "cyber-attack" could shut off the lights, saying they had to defer to more knowledgeable experts in the field of power generation.
The hearing on homeland security aspects of the August blackout took place as chief executives and officials of seven major power generating and distribution companies appeared before a separate House committee to answer questions about the August 14 power failure.