Washington (CNN) -- The military's top officer warned Wednesday of the "substantial" and complex threat to the United States of cyber attack, and the potential for devastating impact.
"We've got to come to a place where those threats are diminished, if not eliminated," Joint Chiefs Chairman Adm. Mike Mullen said at a news conference in Washington. "I would never go in, certainly in any area of warfare, into details on threats except to say they are substantial. We are focused on them."
Mullen said that cyberspace, like outer space, is a lawless terrain.
"It's an area with no rules, there are no boundaries, it happens with the speed of light," Mullen said at the Washington Foreign Press Center.
The U.S. military's Cyber Command wasn't fully up and running until late last year. The first head of that command, Gen. Keith Alexander, was confirmed in May. Alexander has warned that Defense Department computers are probed 250,000 a day. Google has reported it has been the victim of cyber attacks originating in China.
Mullen said China is not the only potential adversary.
"The threat from China is significant," Mullen said. "There are other threats out there that we see routinely... it is an enormously complex and critical area that all of us need to understand a lot better and do a lot more about."