Here’s a legal first that may have been a long time coming: this morning, for the first time ever, the U.S. Justice Department filed criminal charges against foreign officials on counts of cyber espionage.

Five Chinese officials were accused of hacking into American corporations -- within the nuclear, steel and renewable energy industries -- in order to tap valuable trade secrets.

The FBI traced the attacks to unit 61398 of the People’s Liberation Army based in Shanghai, John Carlin, the assistant Attorney General for National Security, revealed at a press conference this morning.

“While the men and women of our American businesses spent their business days innovating, creating, and developing strategies…these members of unit 61398 spent their business days in Shanghai stealing the fruits of our labor,” he said.

Related: Spying 101: How to Figure Out Everything About Your Competition Online

Victims included Alcoa, Allegheny Technologies, SolarWorld, U.S. Steel, the United Steel Workers union and Westinghouse Electric.

While the Obama administration has long objected to the theft of corporate secrets by hackers in China, “This case should serve as a wakeup call to the seriousness of the ongoing cyber threat,” Attorney General Eric Holder said in his remarks this morning. “These criminal charges represent a groundbreaking step forward in addressing that threat.”

As it is unlikely that China will extradite the perpetrators to be tried in the United States, prosecutors have not only named names but provided photos of the suspects in order to shame them, The Wall Street Journal reports -- “a highly unusual” move that has nevertheless been in the works for over a year.

Related: Think China is the No. 1 Country for Hacking? Think Again.