The US Army, Navy and Air Force combined suffered 715 cyber attacks last year, according to a report from the General Accounting Office (GAO) released last week.

The Navy reported the most attacks, 387, with the Army slightly behind at 299. The Air Force suffered only 29 attacks in 2000, according to the report, 'Information Security -- Challenges to Improving DOD's Incident Response Capabilities.'

The report says the three services suffered only 600 cyber attacks in 1999 -- significantly less than the 22,144 electronic assaults reported by the Defense Information Systems Agency (DISA), the Pentagon's IT arm, for that year.

In March of 2000, DISA's then-vice director Major General John Campbell told Congress that there had been a total of 22,144 "incidents" on defense networks in 1999, a figure that's since been widely reported.

A DISA spokesperson could not immediately explain the discrepancy.

But a Pentagon spokesperson said the GAO figures likely reflect actual intrusion attempts, while the DISA numbers include much more.

"My understanding is, they have started to clarify the exact attacks, as opposed to events, like viruses, things of that nature, that were detected in the systems," said Defense Department spokesperson Susan Hansen.

"In other words, 'what were the exact number of identifiable attacks of someone having a purpose of getting into a system that they weren't supposed to be in, as opposed to someone opening a virus message.'"

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