In April 2019, friends reported that the authorities had prohibited Xu from leaving the country. He was stopped from boarding a flight to Japan on a trip authorized and funded by
Tsinghua University. He was defended by other intellectuals, such as
Zi Zhongyun, whose 2019 essay, "Mourning Tsinghua", attacked the action of Tsinghua authorities as the "latest round of '
book burning and burying scholars'". In February 2020, Xu published an essay, "Viral Alarm: When Fury Overcomes Fear", condemning the
Chinese government's response to the
COVID-19 outbreak. Xu describes how the government banned the reporting of factual information during the outbreak and connects this problem to a larger
freedom of speech issue in China. being accused of speaking critically about China's response to the COVID-19 pandemic. He was released from custody on 12 July 2020. Subsequently, Xu was fired from his job at Tsinghua University. Both the US State Department and
High Representative of the Union for Foreign Affairs and Security Policy Josep Borrell, who mentioned Xu in connection with the
709 crackdown, said that the EU: Following his arrest, Xu was blacklisted by vendors, and after his release, he was put on an online blacklist which barred him from receiving donations from the public. In September 2020, artist and book vendor
Geng Xiaonan was arrested together with her husband, ostensibly on charges of illegal business activities, but Xu said it had been because she had spoken out in his support. He put himself at the forefront of an effort by Chinese dissidents to publicize the difficulties of the couple. In an essay published in December 2020, Xu wrote about his experience of being permanently monitored by security cameras in his compound in Beijing; while remaining free, he was not allowed to leave the city. ==References==