The Pentagon has admitted it suffered a major cyber attack in which thousands of files were taken by foreign hackers.

美国五角大楼证实，他们遭受一次较大的网络袭击，数千资料被外国黑客窃取。

Deputy Defence Secretary William Lynn said that in a March attack and other breaches, hackers had taken information on "our most sensitive systems".

The admission came as the Pentagon rolled out a strategy for strengthening US cyber capabilities and addressing threats and attacks in cyberspace.

The plan would treat cyberspace in a similar manner to land, air and sea.

"In the 21st Century, bits and bytes can be as threatening as bullets and bombs," Mr Lynn said, unveiling the plan.

In a speech at National Defense University in Washington, Mr Lynn said about 24,000 files containing Pentagon data were stolen from a defence industry computer network in March, marking one of the largest cyber attacks in US history.

Extracting files

He said at least one attack - a previously revealed 2008 penetration of classified computer systems - had come from a foreign intelligence service, and in an interview ahead of the speech said the Pentagon believed the March attack had been perpetrated（犯，做） by a foreign government.

Previous cyber attacks have been blamed on China or Russia.

"We have a pretty good idea" who did it, he told the Associated Press news agency.

In his speech, he said some of the stolen data was "mundane（世俗的，平凡的） , like the specifications for small parts of tanks, airplanes, and submarines.

"But a great deal of it concerns our most sensitive systems, including aircraft avionics（航空电子设备） , surveillance technologies, satellite communications systems, and network security protocols," he said.

Mr Lynn said cyber attacks in the future would not only focus on stealing data but also damaging US defences or even causing deaths.

He added that virtual intruders have previously tried to extract files related to missile tracking systems and the Joint Strike Fighter.

Though nations like China and Russia have been blamed for many previous cyber attacks, the Pentagon fears terrorist groups could eventually strike American computer networks and steal data.

"Keystrokes originating in one country can impact the other side of the globe in the blink of an eye," Mr Lynn said.