The Pentagon yesterday revealed that a cyber attack earlier this year had led to 24,000 files being stolen from military computers - the largest ever loss of sensitive data.
It identified the attack as having been launched by a foreign government, whom it did not name.
Analysts say this is a dramatic example of why the military was driving a new strategy that included building stronger defenses of its computer networks, collaboration with private industry and new steps to stop "malicious insiders."
Deputy director of defense William Lynn, said in a speech outlining the strategy that 24,000 files containing Pentagon data were stolen from a defense industry computer network in a single intrusion in March. Though he revealed no details about what was taken, he said the Pentagon believed the attacker was a foreign government without naming the country.
In an interview before the speech he said the Pentagon had a pretty good idea who was behind the attack, but did not elaborate.
China and Russia have, in the past, been blamed for several cyber attacks and one of the Pentagon's worst fears is that a terrorist group would somewhere down the line, acquire the ability to not only hack into US computer networks to steal data but to launch attacks in ways that would damage US defences or even cause deaths.