On the bucolic campus of Purdue University in Indiana, deep in America’s heartland and 7,000 miles from his home in China, Zhihao Kong thought he could finally express himself.

In a rush of adrenaline in 2020, the graduate student posted an open letter on a dissident website praising the heroism of the students killed in the Tiananmen Square massacre in 1989.

The blowback, he said, was fast and frightening. His parents called from China, crying. Officers of the Ministry of State Security, the feared civilian spy agency, had warned them about his activism in the United States.

Then other Chinese students at Purdue began hounding him, calling him a CIA agent and threatening to report him to the embassy and the MSS.

Kong, who goes by the nickname Moody, had already accepted an invitation from an international group of dissidents to speak at a coming online commemoration of the Tiananmen massacre anniversary. Uncertain if he should go through with it, he joined in rehearsals for the event on Zoom.

Within days, MSS officers were at his family’s door again. His parents implored him: No public speaking. No rallies.

Moody realised it didn’t matter where he was. The Chinese government was still watching, and it was still in charge. Just before the anniversary event, he reluctantly decided not to give his speech.

“I think that the Zoom rehearsals were known by the Chinese Communist Party,” he said. “I think some of the Chinese students in my school are CCP members. I can tell they are not simply students. They could be spies or informants.”

As the regime of Chinese President Xi Jinping reaches across borders to control its citizens wherever they are, its assaults on academic freedom have intensified, according to U.S. national security officials, academics, dissidents and other experts. Chinese intelligence officers are monitoring campuses across the United States with online surveillance and an array of informants motivated by money, ambition, fear or authentic patriotism. A comment in class about Taiwan or a speech at a rally about Tibet can result in retaliation against students and their relatives back home.

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.” China’s efforts to “suppress free speech and debate on U.S. campuses are concerning,” he said.

At Brandeis University near Boston, Chinese students mobilised in 2020 to sabotage an online panel about atrocities against Uyghurs in the Xinjiang region. Viewers interrupted a Harvard-educated lawyer 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. To the dismay of participants, the university’s leaders failed to condemn the incident.

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.

“It is real: the fear of being constantly watched, of being at risk,” said Chuangchuang Chen, a law student at St. John’s University in New York, whose dissident chat group on the encrypted Telegram platform was hacked. “If there are more than three or four Chinese students in the same class, you are scared to talk. A Chinese student is definitely seen in good favour by the Chinese government for reporting someone.”

U.S. law enforcement agencies have struggled to respond because much of the censorship and harassment occurs in a legal grey area. Victims are often frightened or don’t believe anyone can help. And university administrators are not always eager to intercede because it means risking a lucrative financial stream. U.S. universities have received more than $1 billion in donations from mainland China — from individuals, companies, government organisations — since 2013, according to the Department of Education. That doesn’t include tuition paid by Chinese students, whose numbers in the U.S. reached 370,000 in 2019. Moreover, the complexities of free speech and identity politics make administrators even more reluctant to confront Chinese state influence.

“It is easier to take a stance against the United States than against China,” said Rayhan Asat, the Uyghur scholar who was the target of the incident at Brandeis. “That is what is happening at U.S. universities. They are self-censoring themselves in order to recruit Chinese students for economic benefit.”

As a result, no one is doing much to prevent persecution by a foreign dictatorship in supposed bastions of learning and freedom, said U.S. national security officials, academics, dissidents and other experts.

“This is an overall extension of the police state,” said Anna Puglisi, a senior fellow at Georgetown University who served until last year as the U.S. intelligence community’s national counterintelligence officer for East Asia. “It is brazen. But when you talk about it, people act as if you’re nuts. There has been no cost to China for this.”

In 2019, university and national security officials met at a coastal resort in Maryland to discuss China-related threats. Many of the educators seemed oblivious to the repression in their midst, participants said. One skeptical administrator had never even heard of WeChat, the ubiquitous social media app used by Chinese students to communicate and by their government to shadow them, said Sophie Richardson, the China director of Human Rights Watch, who spoke at the conference.

“You realized how poorly understood some mainland students’ experiences are at U.S. universities,” Richardson said. “If the mainland students aren’t enjoying academic freedom to the same extent as others, that means universities are failing them. There is a certain amount of denial and a remarkable lack of awareness.”

Several university leaders who attended the conference declined to be interviewed. A rift between universities and the government over China worsened during President Donald Trump’s administration, whose policies were seen as hawkish and even racist by critics in academia. When then-Secretary of State Mike Pompeo gave a speech in December raising the spectre of China meddling on U.S. college campuses — from stealing secrets to censoring students — some university officials dismissed it as overblown rhetoric.

“The reaction I was getting was: ‘This hostility with China, it’s Trump-driven. It will go away,’” said one U.S. intelligence official who talks with university leaders. “I said, ‘As long as Xi Jinping is in power, it will get worse.’”

Some educators, even China experts, warn against exaggerating the scope of the threat. Professor James Millward of Georgetown University, a historian of Xinjiang and critic of China’s repression there, witnessed the abuse of Asat at Brandeis. But he said he hasn’t seen that kind of aggressiveness in his own classes.

“I don’t have experience, in my teaching, of disruptions or hyper-nationalistic students,” Millward said. “My students and their parents are more concerned about anti-Asian hate, being attacked on the street. Most Chinese students just want to get educated and get on with their business.”

But recent studies by Human Rights Watch and the French Defense Ministry highlight increasing activity that exploits democratic freedoms across North America, Australia and Europe. Pro-China forces on campuses have assaulted, stalked, threatened and doxxed dissidents and scholars. Last month in Germany, a publishing company said pressure from Chinese diplomats caused two universities to cancel presentations of a biography of Xi written by German journalists.

The Chinese Embassy in Washington did not respond to ProPublica’s requests for comment. In the past, Chinese officials have denied allegations that they engage in censorship and spying at foreign universities.

To assess the extent of Chinese repression on U.S. campuses and the limits of the response, ProPublica interviewed Chinese students and scholars and reviewed emails, texts and other online communications that documented their experiences. ProPublica also spoke with current and former national security officials, educators, human rights advocates and other experts in the United States and overseas, and reviewed reports by governments, academics and human rights groups.

Most experts say U.S. and university officials could, and should, be doing more. Just as colleges shut down fraternities for hazing and other misconduct, they should crack down on wrongdoing by Chinese students associations, which often lead the attack on fellow students and proclaim their cooperation with the Chinese regime, the U.S. intelligence official said.

“I used to think universities were victims,” the intelligence official said. “But now I think those that take money from China and don’t protect their students from [People’s Republic of China] harassment may be complicit.”