At least 154 Chinese scientists who worked on government-sponsored research at the U.S.’s foremost national security laboratory over the last two decades have been recruited to do scientific work in China — some of which helped advance military technology that threatens American national security — according to a new private intelligence report obtained by NBC News.

The report, by Strider Technologies, describes what it calls a systemic effort by the government of China to place Chinese scientists at Los Alamos National Laboratory, where nuclear weapons were first developed.

Many of the scientists were later lured back to China to help make advances in such technologies as deep-earth-penetrating warheads, hypersonic missiles, quiet submarines and drones, according to the report.

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Scientists were paid as much as $1 million through participation in Chinese government “talent programs,” which are designed to recruit Chinese scientists to return to China. Such talent programs have long been identified as a source of concern, but U.S. officials said they had not previously seen an unclassified report that described the phenomenon in such detail, naming specific scientists and the projects they have worked on.

Read more: NBC