NEW YORK - Other nations are increasingly employing cyber attacks without "any sense of restraint," a top US cyber-security official said on Friday, citing "reckless" behaviors that neither the United States nor the Soviet Union would have dared at the height of Cold War tensions.

Debora Plunkett, head of the National Security Agency's Information Assurance Directorate, the agency's cyber-defense arm, told a forum at the Polytechnic Institute of New York University that "we're starting to see nation-state resources and expertise employed in what we would characterize as reckless and disruptive, destructive behaviors."

Officials from the Obama administration and Congress have called for stronger cyber security, accusing China and Russia of hacking US computer networks for economic gain, espionage and other motives.

When asked how large a threat hacking from China, Russia and other countries posed to the United States, Plunkett said: "Significant. I don't know how else to describe it."

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