The indictment accused members of the People's Liberation Army, the military of the People's Republic of China, of participating in cyber-espionage on behalf of a foreign government, according to the 48-page indictment.
Wang Dong, Sun Kailiang, Wen Xinyu, Huang Zhenyu and Gu Chunhui are accessed of hacking into private-sector companies, including Western Pennsylvania companies U.S. Steel, Alcoa and Westinghouse Electric, to gain trade secrets and steal information.
"To our knowledge, no material information was compromised during this incident which occurred several years ago. Safeguarding our data is a top priority for Alcoa and we continue to invest resources to protect our systems," said Monica Orbe, a spokesperson for Alcoa.
U.S. Attorney General Eric Holder, U.S. Attorney David Hickton, Assistant Attorney General John Carlin and FBI Executive Associate Director Robert Anderson were scheduled to speak at a press conference in Washington, D.C., at 10 a.m.
Carlin, recently installed as head of the Justice's National Security Division, this year cited prosecution of state-sponsored cyber-threats as a key goal for the Obama administration.
U.S. 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 that it faces a major threat from hackers, and the country's military is believed to be among the biggest targets of the NSA and U.S. Cyber Command.
Beijing has in the past repeatedly denied allegations that its hackers have targeted foreign websites but says China is a major victim of cyberattacks and is opposed to any form of cyber hacking.
It says it wants to see global cooperation in fighting cybercrimes instead of allegations.
“China not only does not support hacking but also opposes it,” Premier Li Keqiang said last year in a news conference when asked if China would stop hacking U.S. websites. “Let's not point fingers at each other without evidence but do more to safeguard cyber security.”
Earlier this year, China set up an Internet security group led by President Xi Jinping. State media have described the Internet as a battleground, where cyber safety is essential to state security.
Last September, President Barack Obama discussed cybersecurity issues on the sidelines of a summit in St. Petersburg, Russia, with Chinese President Xi Jinping.
White House spokesman Ben Rhodes said at the time that Obama had addressed concerns about cyber threats emanating from China. He said Obama told Xi the U.S. sees it not through the prism of security but out of concern over theft of trade secrets.
In late March, Defense Secretary Chuck Hagel revealed that the Pentagon planned to more than triple its cybersecurity staff in the next few years to defend against Internet attacks that threaten national security.
Hagel's comments at the National Security Agency headquarters in suburban Washington came as he prepared to visit China.
“Our nation's reliance on cyberspace outpaces our cybersecurity,” 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.”