The United States said Wednesday that it had disrupted a Chinese hacking operation responsible for break-ins at the U.S. Justice Department, NASA, the Federal Reserve, the U.S. Senate, and other sensitive government agencies.

In a statement, the Justice Department said that it had seized domains used by two hacking platforms, dubbed “QScan” and “QTRouter,” which it said had been used as part of the campaign. An affidavit identified the U.S. Department of Energy, the Department of Health and Human Services, the National Institutes of Health, and four unnamed companies in the United States and South Korea as being among the hackers’ victims.

The Chinese Embassy in Washington did not immediately return a message seeking comment. Beijing routinely denies responsibility for hacking activity.

The Justice Department said that the platforms were run by a China-based firm, the Nanjing Xinjiuwei Network Technology Company, whose clients it said included China’s civilian intelligence agency, the Ministry of State Security and its military, the People’s Liberation Army.

Reuters could not immediately locate contact details for Nanjing Xinjiuwei.

The affidavit said the group’s computer infrastructure had been used to compromise critical infrastructure and other sensitive networks in the U.S. and worldwide since at least 2018.

Experts who follow Chinese cyber activity say that private contractors routinely carry out high-profile intrusions on behalf of various Chinese government agencies.

“Over the last decade, the number of companies offering niche offensive services has exploded,” said Dakota Cary, a China analyst with cybersecurity company SentinelOne.

(Reporting by AJ Vicens and Raphael Satter; Additional reporting by Bhargav Acharya, Katharine Jackson and David Shepardson; Editing by Caitlin Webber, Chizu Nomiyama and Daniel Wallis)