The letter from Purdue University President Mitch Daniels last week was unflinching, unapologetic and unusual.

In a Dec. 15 letter to faculty, staff and students, Daniels described his regret that he’d had to learn from a ProPublica article that a Chinese graduate student had been harassed by other Chinese students and that his parents in China had been visited by the Ministry of State Security — all because the graduate student had spoken out “on behalf of freedom and others martyred for advocating it.”

Daniels condemned the “atmosphere of intimidation” as “unacceptable and unwelcome” on the Indiana campus. He warned that the students who’d made the threats would face disciplinary action and any student who “reported another student to any foreign entity for exercising their freedom of speech or belief will be subject to significant sanction.”

No value, the university president wrote, was more central than the freedom of inquiry and expression.

“Those seeking to deny those rights to others, let alone collude with foreign governments in repressing them, will need to pursue their education elsewhere,” Daniels concluded.

The bluntly phrased letter followed a ProPublica story last month that detailed how the regime of Chinese President Xi Jinping is ramping up efforts to control its citizens wherever they are, even on U.S. campuses, according to U.S. national security officials, academics, dissidents and other experts. Chinese intelligence officers are using online surveillance and an array of informants motivated by money, ambition, fear or authentic patriotism to track perceived dissident activity at American universities.

Students who don’t conform to the “views and ideology of the Chinese Communist Party,” said Mike Orlando, who leads the U.S. National Counterintelligence and Security Center, “risk being targeted for harassment.”

The ProPublica story described the chilling experiences of students on several campuses, as well as that of a Harvard-educated Uyghur lawyer. It revealed that administrators are often reluctant to acknowledge or resist these assaults on academic freedom because U.S. universities receive hundreds of millions of dollars in donations from China and tuition from Chinese students.

At Brandeis University, near Boston, Chinese students last year sabotaged an online panel about atrocities against Uyghurs in the Xinjiang region. Viewers interrupted human rights lawyer Rayhan Asat as she tried to describe her brother’s plight in a concentration camp, scrawling “bullshit” and “fake news” over his face on the screen and blaring China’s national anthem. Afterward, the university’s leaders failed to condemn the incident.

And at the University of Georgia, a graduate student became the prey of an intelligence officer in China who pressured him over the phone to become a spy and inform on fellow dissidents in America. When the student made the conversations public, Chinese security forces harassed his family back home.

ProPublica’s story was picked up around the world. Daniels’ response to it compelled the Wall Street Journal’s editorial board to weigh in last week, calling his approach “refreshing.”

Human rights advocates who track cross-border Chinese repression said Daniels’ statement went beyond the usual generalities about the importance of free speech. The letter set a precedent, they said, by essentially warning students who engage in harassment that the university would not be cowed by financial considerations and would crack down on those who act as agents of the regime in Beijing.

In Australia, which has experienced conflict over the long-distance repression of Chinese students by their government, the Purdue letter struck a chord with Clive Hamilton, a professor of public ethics at Charles Sturt University in Canberra and an expert on Chinese influence operations worldwide. “It’s hard to imagine any Australian university making a statement like this one,” Hamilton wrote on Twitter.

At Brandeis, ProPublica’s account of the disruption of Asat’s Zoom talk also caused a reaction. Brandeis President Ronald Liebowitz sent a letter to university faculty saying that “in hindsight I do agree that the Zoom bombing during this particular event, which was an attack on free expression and the pursuit of truth, should have drawn a swift response.”

“While the statement from President Liebowitz was long overdue, he did finally acknowledge the assault against me, a human rights advocate and lawyer, is an attack against academic freedom and free speech,” Asat said Monday. “Universities should welcome international students while defending the integrity of academic freedom enshrined in the University principles. Let’s bear in mind, freedom of speech is important for international students wishing to be exposed to opinions that are literally illegal at home.”

And Zhihao Kong, the grad student at the center of the furor at Purdue, also spoke out. Kong had faced harassment from Chinese students after posting an online letter praising 1989 Tiananmen Square protests. In an open letter last week, he thanked Daniels and others who have publicly defended him. He told his fellow Chinese students that they should all enjoy academic freedom, whether they are pro-democracy activists or supporters of the Chinese Communist Party.

“In my world there’s always a place for you,” he told pro-regime students. “You can disagree with me; you can even insult me.” But those who collude with their government in spying and repression, he said, are “crossing the line.”

Update, Dec. 20, 2021: This story has been updated to include a response from Uyghur human rights lawyer Rayhan Asat.