More than 1,000 Chinese researchers have left the United States amid a U.S. crackdown on alleged technology theft, John Demers, the U.S. Justice Department's top national security official, said Wednesday.

William Evanina, chief of the counterintelligence branch of the office of the U.S. Director of National Intelligence, told the same Aspen Institute Cyber Summit that Chinese agents already were targeting personnel of the incoming administration of President-elect Joe Biden, as well as "people close" to Biden's team.

A Justice Department official said the researchers to which Demers referred were a different group than those mentioned by the State Department in September, when it said the U.S. had revoked visas for more than 1,000 Chinese nationals under a presidential measure denying entry to students and researchers deemed security risks.

China described that move as "naked" political persecution and racial discrimination that seriously violated human rights.