Probably with respect to policies clarified and enacted with respect to the JASON report the NSF commissioned last year (given the context):

https://nsf.gov/news/special_reports/jasonsecurity/NSF_respo...

They mention the case of Charles Leiber [1] which might be informative.

[1] https://en.wikipedia.org/wiki/Charles_M._Lieber#Federal_arre...

> Lieber stated that "he was never asked to participate in the Thousand Talents Program", adding that "he 'wasn't sure' how China categorized him." The DOJ believes that Lieber's statement was false, because an intercepted email dated June 27, 2012, from Wuhan University of Technology ("WUT") included a contract for Lieber to sign.

I wonder what other evidence they have here, eg him actually receiving funds from them ... if a Chinese university sends you a recruiting email and it goes to your spam folder, and then you say you have no affiliation with them, can you be indicted for that based on an "intercepted email"? One would hope not!

According to the DOJ press release from January, "under the terms of Lieber’s three-year Thousand Talents contract, WUT paid Lieber $50,000 USD per month, living expenses of up to 1,000,000 Chinese Yuan (approximately $158,000 USD at the time) and awarded him more than $1.5 million to establish a research lab at WUT." [1]

I suspect they had evidence to indicate he was paid, but couldn't produce specific financial records to prove it without a doubt. In cases like this, the FBI typically goes for the jugular by pursuing espionage charges. This can be difficult because it often requires concrete evidence of financial gain from the foreign entity explicitly for the information provided or actions taken. The mere appearance of financial gain is not enough, they'd want to see the literal check stubs and account statements.

[1] https://www.justice.gov/opa/pr/harvard-university-professor-...