US justice department charges Chinese with hacking

Attorney General Eric Holder said the alleged breaches were "significant" and demanded "an aggressive response".

US prosecutors say the officers stole trade secrets and internal documents from five companies and a labour union.

China has previously denied hacking the US and said it faces similar attacks.

Potentially more victims

Table showing the industries most often targeted by the hackers

In Washington on Monday, Mr Holder said the hacking charges laid against the Chinese nationals were the first against "known state actors for infiltrating US commercial targets by cyber means".

He identified the alleged victims as Westinghouse Electric, US Steel, Alcoa Inc, Allegheny Technologies, SolarWorld and the US Steelworkers Union.

"The alleged hacking appears to have been conducted for no reason other than to advantage state-owned companies and other interests in China, at the expense of businesses here in the United States," Mr Holder said.

In an indictment in the western district of Pennsylvania, the heart of the US steel industry, the US named Wang Dong, Sun Kailiang, Wen Xinyu, Huang Zhenyu, and Gu Chunhui, all officers in Unit 61398 of the Chinese People's Liberation Army (PLA), as the alleged conspirators.

FBI officials said the hacking, in the years 2006-14, caused "significant losses" at the companies and that there were likely many more victims.

And Mr Holder said the US government "categorically denounces" economic espionage as a trade tactic.

What is Unit 61398?

Man walks past the building identified by Mandiant as the likely source of cyber attacks on 19 February 2013

A unit of China's People's Liberation Army, to whose Shanghai address US cyber security firm Mandiant says it traced a prolific hacking team
The team was said to have hacked into 141 computers across 20 industries, stealing hundreds of terabytes of data
Mandiant says the team would have been staffed by hundreds, possibly thousands of proficient English speakers
China said Mandiant's report was flawed and lacked proof

"As President Obama has said on numerous occasions, we do not collect intelligence to provide a competitive advantage to US companies, or US commercial sectors," Mr Holder said.

John Carlin, head of the justice department's national security division, said, "For the first time, we are exposing the faces and names behind the keyboards in Shanghai used to steal from American businesses."

"While the men and women of our American businesses spent their business days innovating, creating, and developing strategies to compete in the global marketplace, these members of unit 61398 spent their business days in Shanghai stealing the fruits of our labour," Mr Carlin said.

For example, Mr Carlin said that as SolarWorld was rapidly losing market share to cheaply priced Chinese competitors, the hackers were stealing documents on pricing strategy from them, and while Westinghouse was negotiating a deal with a Chinese state-owned firm to build nuclear power plants, Unit 61398 stole secret designs for plant components.

"In the past, when we brought concerns such as these to Chinese government officials, they responded by publicly challenging us to provide hard evidence of their hacking that could stand up in court," Mr Carlin said. "Well today, we are."

In March, Defence Secretary Chuck Hagel said the Pentagon planned to more than triple its cyber-security capabilities in the next few years to defend against such internet attacks.

US President Barack Obama has called cyber attacks a "real threat" to US security and its economy.