Japan has scolded its biggest weapons supplier, Mitsubishi Heavy Industries, for failing to immediately report a cyber attack on its computers, amid fears that a number of Japanese defense contractors are being targeted by hackers.
Defense officials only learned of the August cyber attack from Japanese media reports Monday. A defense official told Reuters that Mitsubishi Heavy, as a defense contractor, is obliged under contract to inform the government promptly of any breach of sensitive information.
Viruses were discovered last month on more than 80 of Mitsubishi Heavy's servers and computers. Computer systems at Mitsubishi Heavy had been accessed and some network information may have been leaked, the company admitted Monday.
The cyber attack was reportedly targeting data on missiles, submarines and nuclear power plants, the BBC reports.
But the Japanese government says that no sensitive information was leaked.
Mitsubishi Heavy has built the U.S.-designed F-15 fighter jet and missile systems including Patriot batteries under license, Reuters says.
China's foreign ministry on Tuesday dismissed suggestions that the hacking attack could have originated in China, Reuters reports.
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"The Chinese government has consistently opposed hacking attack activities. Relevant laws strictly prohibit this," foreign ministry spokesman Hong Lei told reporters at a press briefing in Beijing.
"China is one of the main victims of hacking ... Criticizing China as being the source of hacking attacks not only is baseless, it is also not beneficial for promoting international cooperation for internet security."
Two other Japanese military contractors, IHI Corp., a supplier of engine parts for fighter planes, and Kawasaki Heavy Industries, a maker of airplanes, helicopters and rocket systems, said its employees have been receiving a growing number of suspicious virus-tainted emails.