The US has revoked the visas of more than 1,000 Chinese students and researchers it said had ties to the Chinese military, accusing some of espionage, in the latest dispute between the rival superpowers. China had been “abusing student visas to exploit American academia”, said Chad Wolf, acting secretary for the Department of Homeland Security, in a speech on Wednesday. “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.”