The Department of Justice on Friday announced indictments against nine hackers linked to the Iranian government for a four-year effort to steal research and other intellectual property from around 8,000 professors at hundreds of American and foreign universities. The hacks also allegedly targeted 30 private companies and five government agencies, including the Department of Labor and the Hawaii state government.

The U.S. attorney for the Southern District of New York, Geoffrey Berman, called the series of thefts “one of the largest state-sponsored hacking campaigns ever prosecuted by the Department of Justice.” The DOJ accused seven Iranians in 2016 of launching a series of distributed denial of service (DDoS) attacks against the financial sector, though the department’s indictment this time around is much more extensive.

The nine alleged hackers are all affiliated with the Mabna Institute, a tech firm that conducts cyber-attacks for Iranian universities and the Iranian Revolutionary Guard Corps, according to the DOJ. From 2013 to 2017, officials say they managed to abscond with 31 terabytes of data, worth $3.4 billion, from 144 American universities. They also allegedly hit 176 foreign universities.

None of the people charged has been detained, though the DOJ notes that they may be arrested if they ever leave Iran. The Treasury Department has also levied sanctions against the Mabna Institute and the alleged hackers.