A real life cyber war between nation states has already happened

Bill Gertz:

NSA: Nation State Cyber Attack Included Virtual ‘Hand-to-Hand Combat’

Deputy NSA chief says government bureaucracy harming response to cyber threats

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"It was a nation state actor who had gotten in and what we saw for the very first time, the adversary, once we detected them, instead of disappearing they fought back," Ledgett said during a conference on cyber threats.

"So it was basically hand-to-hand combat in a network where we would take an action [and] they would then counter that," he said.
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"Actually one of the advantages NSA brings to this is our defenders also have access to our foreign intelligence capabilities so we were out in adversary space so we were able to see them teeing up new things to do," Ledgett said.
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It appears to have mainly been a defensive battle.  I would like to see a counter attack that would destroy the computer operations of the aggressor.