The federal government on Monday unsealed espionage indictments targeting five Chinese military officials it accused of hacking into computer systems run by Alcoa Inc., United States Steel Corp., Westinghouse Electric Co. and other U.S. corporations.

The accused hackers, members of the Chinese People’s Liberation Army, face 31 criminal counts relating to the use of cyberespionage to steal trade secrets and other U.S. business information in the nuclear power, solar energy and metals industries to benefit Chinese companies. The military officials, using aliases including “UglyGorilla,” “WinXYHappy” and “KandyGoo,” allegedly targeted the U.S. organizations from at least 2006 until this year. In addition to Alcoa, U.S. Steel and Westinghouse, the organizations include Allegheny Technologies Inc., SolarWorld A.G.’s U.S. subsidiaries and the United Steelworkers.