The attack was detected on Wednesday in the unclassified e-mail system of the office of the secretary of defense, which employs thousands of employees.
Few details of the attack were released, though Secretary Gates says, "We obviously have redundant systems in place... There will be some administrative disruptions and personal inconveniences."
When asked if his own e-mail account was affected, Gates said, "I don't do e-mail. I'm a very low-tech person," according to the Associated Press.
Gates adds that such cyber attacks are almost a daily occurrence at the Pentagon, with over a hundred attacks detected per day. He adds that this one had no adverse impact on department operations and that the systems should be up and running soon.