The commander of the new US Cyber Command, Army General Keith Alexander, said the Pentagon's vast computer system is probed by potential enemies a quarter-of-a-million times every hour and needs to be protected, especially in a time of war. Alexander testified Thursday before a US Congressional panel.

Within the US Department of Defense, there are some 15,000 different computer networks, including 7 million computing devices on hundreds of military installations around the world.

General Alexander told members of the House of Representatives Armed Services Committee that those computer systems are at risk.

"We face severe threats. Those threats to our national security in my opinion are real. It is occupying much of our time and attention. At the unclassified level, we have stated that we see probes and scans to our networks that come up on the order of 250,000 times an hour," said Alexander.

Recently, the Defense Department revealed new details about a major cyber attack in 2008 that allowed hackers to transfer data to servers under foreign control. Defense officials say that intrusion served as a wakeup call. The following year, Cyber Command was created to defend the Pentagon's computer networks.

General Alexander, who also serves as the director of the National Security Agency, said that since the inception of the Internet, the key problems have been activity by hackers, and exploitation of private and sensitive information.

"That is where someone comes in and takes information from your computer, steals your credit card number, takes money out of your account. We have seen that go on and that endures, and it is perhaps the most significant form of the threat that we see today - not just stealing our intellectual property, but also our secrets and other parts of our networks," said Alexander.

Alexander warned that deterring enemies in the cyber world will not be easy and could take years to achieve. He said the government needs to work with private industry to ensure that the nation's critical infrastructure is protected.

"What concerns me the most is destructive attacks that are coming. We are concerned that those are the next things that we will see. And those are things that can destroy equipment, so it is not something that you recover from by just stopping the traffic. It is something that breaks a computer or another automated device," said Alexander.

Alexander said that if such damage occurred in a war zone, the Pentagon's command and control systems would suffer.

He said the Pentagon has sent an expeditionary cyber support team to Afghanistan to protect computer networks and programs being used in the fight against the Taliban and al-Qaida.

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（来源：VOA 编辑：陈丹妮）