“He said, ‘I need to figure out how to take myself off as the P.I., the principal investigator, if that’s going to compromise our project’s chances of being accepted,’” Ms. Atkins said, declining to name the academic for fear of jeopardizing his proposal. The professor, she added, was even considering withdrawing from the project completely to avoid holding back his co-researchers.

It is a sentiment that some, such as Representative Judy Chu, Democrat of California, believe underscores a tone of racism behind the policy change. The restrictions, she said, equate to targeting “an entire ethnic group of people for suspicion that they’re spies for China.”

“I think we should take specific security threats seriously, but each of those threats should be identified by the threat, not by racial groups,” said Ms. Chu, the chairwoman of the Congressional Asian Pacific American Caucus.

Since June 11, the State Department has been restricting visas for Chinese graduate students studying in sensitive research fields to one year, with the chance to reapply every year. The move rolls back an Obama-era policy that allowed Chinese citizens to secure five-year student visas.

Le Fang, a Ph.D. student from China studying computer science at the University at Buffalo, locked up a five-year F-1 visa in 2015. But the new policy could hurt his friends whose visas recently expired, he said. They may have to fly back to China to get new visas, and they risk denials partway through their academic career.