"The Chinese military hacked into a Pentagon computer network earlier this year in the most successful cyber attack ever on the US defence department, according to US officials.
The Pentagon acknowledged shutting down part of a computer system serving the office of Robert Gates, the defence secretary, in June, but refused to say who it believed had been behind the incursion.
Current and former officials have now told the Financial Times that an internal investigation into the attack has revealed it came from the Peoples’ Liberation Army.
One senior US official said the Pentagon had pinpointed the exact origins of the attack. Another person familiar with the event said there was a “very high level of confidence ...trending towards total certainty” that the PLA was responsible.
The Defence Ministry in Beijing declined to comment on Monday.
Angela Merkel, Germany’s chancellor, raised reports of Chinese infiltration of German government computers with China’s premier, Wen Jiabao, in a recent visit to Beijing, after which the Chinese foreign ministry said the government opposed and forbade ”any criminal acts undermining computer systems, including hacking”. "