The United States has brought cyber-espionage charges against five Chinese military officials accused of hacking into American companies to gain trade secrets.
US Attorney General Eric Holder claimed the officials hacked into six nuclear power, metals and solar products firms.
He said the companies affected were Alcoa World Alumina, Westinghouse Electric, Allegheny Technologies, US Steel, United Steelworkers Union and SolarWorld.
The charges have been described as unprecedented and dramatise a long-held Obama administration goal to prosecute state-sponsored cyber threats.
Mr Holder said the US will not tolerate foreign government efforts to sabotage American companies.
US officials have accused China’s army and China-based hackers of launching attacks on American industrial and military targets, often to steal secrets or intellectual property. China has said it faces a major threat from hackers, and the country’s military is believed to be among the biggest targets of the NSA and US Cyber Command.
Last September, US President Barack Obama discussed cyber-security issues on the sidelines of a summit in St Petersburg, Russia with his Chinese counterpart Xi Jinping.
White House spokesman Ben Rhodes said at the time that Mr Obama had addressed concerns about cyber threats emanating from China.
He said the president told Mr Xi that the US sees it not through the prism of security but out of concern over theft of trade secrets.
In late March, US Defence Secretary Chuck Hagel revealed that the Pentagon planned to more than triple its cyber-security staff in the next few years to defend against internet attacks that threaten national security.
Mr Hagel’s comments at the National Security Agency headquarters came as he prepared to visit China.
“Our nation’s reliance on cyberspace outpaces our cyber-security,” Mr Hagel said at the time.
“Our nation confronts the proliferation of destructive malware and a new reality of steady, ongoing and aggressive efforts to probe, access or disrupt public and private networks, and the industrial control systems that manage our water, and our energy and our food supplies.”
The move “indicates that Department of Justice has evidence and is willing to bring it to a court of law and be more transparent,” said Frank Cilluffo, head of the Homeland Security Policy Institute at the George Washington University.
American officials have long been concerned about hacking from abroad, especially China. Secret US State Department cables obtained by WikiLeaks traced major systems breaches to China, Reuters reported in 2011. One 2009 cable pinpointed attacks to a specific unit of China’s People’s Liberation Army.
Such charges are symbolic but the move would prevent the individuals indicted from travelling to the United States or other countries that have an extradition agreement with it.
An FBI official last week warned of multiple cyber security-related cases, including indictments and arrests, in the coming weeks.
On Sunday, a top Chinese Internet official called for Beijing to tighten its own cyber security, citing “overseas hostile forces.