The United States has revoked visas for more than 1,000 Chinese nationals under a presidential measure denying entry to students and researchers deemed security risks, the State Department said on Wednesday, a move China called a violation of human rights.

The acting head of the U.S. Department of Homeland Security, Chad Wolf, said earlier that Washington was blocking visas “for certain Chinese graduate students and researchers with ties to China’s military fusion strategy to prevent them from stealing and otherwise appropriating sensitive research.”

In a speech, Wolf repeated U.S. charges of unjust business practices and industrial espionage by China, including attempts to steal coronavirus research, and accused it of abusing student visas to exploit American academia.

Wolf said the United States was also “preventing goods produced from slave labor from entering our markets, demanding that China respect the inherent dignity of each human being,” an apparent reference to accusations of abuse of Muslims in western Xinjiang.

A State Department spokeswoman said the visa action followed a May 29 proclamation by President Donald Trump as part of the U.S. response to China’s curbs on democracy in Hong Kong.

“As of September 8, 2020, the department has revoked more than 1,000 visas of PRC nationals who were found to be subject to Presidential Proclamation 10043 and therefore ineligible for a visa,” she said.

She said the ineligible “high-risk graduate students and research scholars” were “a small subset” of the Chinese coming to the United States for study and research, and that legitimate students and scholars would continue to be welcomed.

About 360,000 Chinese nationals study in the United States, bringing its colleges significant revenue, though the COVID-19 pandemic has severely disrupted the return to campus this autumn semester.

In Beijing on Thursday, a foreign ministry spokesman described the U.S. move as “naked” political persecution and racial discrimination that seriously violated human rights.

“China reserves the right to make a further response on this issue,” Zhao Lijian told a daily media briefing.

Deteriorating relations

China-U.S. relations have sunk to historic lows with the world’s two biggest economies clashing over issues ranging from trade and human rights to Hong Kong and the coronavirus.

Trump, who had touted friendly ties with Chinese President Xi Jinping as he sought to make good on promises to rebalance a massive trade deficit, has made getting tough on China a key part of his campaign for re-election on Nov. 3.

He has accused his Democratic opponent, Joe Biden, who leads in national opinion polls, of being soft toward Beijing.

Some Chinese students enrolled in U.S. universities said they learnt of the cancellations in emailed notices received on Wednesday from the U.S. embassy in Beijing or consulates in China.

In a WeChat chatrooom, more than 70 holders of F-1 visas, both postgraduates and undergraduates, said the notices advised them to seek new visas if they wanted to travel to the U.S.

Many said they were majoring in subjects such as science, technology, engineering and mathematics. Some said they had secured bachelor’s degrees at Chinese universities with links to the People’s Liberation Army.

A final-year undergraduate student of the University of Illinois at Urbana-Champaign expressed shock at getting the notice.

The only reason he could think of could be prior experience at the Beijing University of Posts and Telecommunications (BUPT), he said. The university is known for its defense and security technology research.

“I studied at BUPT before year two, but I have no connections with that university since,” he told Reuters, on condition of anonymity as the subject is sensitive.