It added that the cyber-criminals responsible were now targeting home internet users after initially focusing on professionals.
"They were incredibly careful, and patient," a source familiar with the investigation told the New York Times, adding that the US intelligence agencies "couldn't really understand the severity" of the cyber-attack being planned until it began on 24 November.
"It's people coming into browse," said William Lynch, general manager of HSN.com, who added that the purchases on Cyber Monday in 2006 "were not as high as we wanted".
He added that the country has set up a cyber-taskforce responsible for assessing threats to key infrastructure such power production and water supplies.
Orde added that the risks presented by groups such as Anonymous and cyber-criminals were leading to a new brand of policing so sophisticated that it made the current generation "look like complete amateurs".
Scott Aaronson, Senior Director of National Security Policy at Edison Electric Institute added that cyber is relatively new as a critical infrastructure -- which moderator Matthew L. Wald of The New York Times said made it the "glass jaw of American life" -- but that his industry is working hard on risk management.
Coats named Russia, China, Iran and North Korea as cyber aggressors against the U.S., adding that "Russia has been the most aggressive foreign actor, no question".
Steve Schank, a Zantaz spokesman, added: "Some of the cyber documents never really exist.
"From our observations, it is one of the most prolific cyber espionage groups in terms of the sheer quantity of information stolen," it said, adding that it was "likely government-sponsored and one of the most persistent of China's cyber threat actors".
"The government blocks oppositional websites and arrests and imprisons cyber-dissidents," it said, adding that "self-censorship remains widely practiced by both online and offline media for fear of government retribution".
