The United States is blocking visas for certain Chinese graduate students and researchers to prevent them from stealing sensitive research, the acting head of the U.S. Department of Homeland Security, said on Wednesday.

Chad 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.

“We are 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,” he said in a speech in Washington.

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 alleged abuses of Muslims in China’s Xinjiang region.

Wolf did not give details.

U.S. Customs and Border Protection officials have prepared orders to block imports of cotton and tomato products from Xinjiang over accusations of forced labor, though a formal announcement has been delayed.

Sino-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.

U.S. President Donald 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 most opinion polls, of being soft toward Beijing.

Earlier, some Chinese students enrolled in U.S. universities said they received emailed notices from the U.S. embassy in Beijing or U.S. consulates in China on Wednesday informing them that their visas had been canceled.

Nearly 50 students holding F-1 academic visas including postgraduates and undergraduates said in a WeChat chatroom the notices stated they would have to apply for new visas if they wanted to travel to the United States.

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

In late May, sources with knowledge of the matter told Reuters Washington was planning to cancel the visas of thousands of Chinese graduate students believed to have links to China’s military.

Reuters