The US has charged a Harvard professor and two Chinese researchers based in Boston with assisting the Chinese government.
Harvard department chair Charles Lieber is accused of lying about his connections, while the researchers were charged with being foreign agents.
Mr Lieber allegedly accepted more than $1m in grant money from the Chinese government.
Harvard University called the charges against him “extremely serious”. In a statement, the university added: “Professor Lieber has been placed on indefinite administrative leave.”
Prosecutors said Yanqing Ye, a Boston University robotics researcher, concealed the fact that she was in the Chinese army.
Ms Ye is accused of falsely identifying herself as a student and also continuing to work for the People’s Liberation Army, while completing a number of assignments in the US.
Cancer researcher Zaosong Zheng was arrested at Boston Logan International Airport with 21 vials of biological samples in his bag. Prosecutors allege he was planning to return to China to continue his research there.
Court documents allege Mr Lieber, who has worked as the head investigator at the Lieber Research Group at Harvard University, received more than $15m (£11.5m) in grants from the US National Institute of Health and the US Department of Defence.
Recipients of these grants have to disclose any conflicts of interest, including financial support from foreign governments or organisations.
However in 2011, allegedly without Harvard’s knowledge, Mr Lieber joined Wuhan University of Technology in China as a scientist.
According to the court papers, he also participated in the Thousand Talents Plan, a programme that aims to attract foreign research specialists. The US has flagged the programme as a security concern in the past.
From his role at Wuhan University of Technology, Mr Lieber was given a monthly salary of $50,000, in addition to living expenses of up to $158,000.
The filings say he was also given more than $1.5m to establish a research lab at Wuhan University of Technology and, in return, was expected to work for the university, applying for patents and publishing articles in its name.
The court filings claim Mr Lieber failed to disclose this information and during an interview with investigators, lied about his involvement in the Thousand Talents plan and his affiliation with the university in Wuhan.
Andrew Lelling, US attorney for the district of Massachusetts, said in a press conference: “This is a very directed effort by the Chinese government to fill what it views as its own strategic gaps.”