According to the Justice Department, Wu noticed someone posting fliers on October 22 near the university bearing messages that read “Stand with Chinese People”, “We Want Freedom”, and “We Want Democracy”.

The Justice Department did not identify the victim or their nationality. But they are presumably Chinese given that, as part of his harassment, Wu allegedly told her that he had informed the People’s Republic of China’s public security bureau, which would greet her family back home.

“I already called the tip-off line in the country, the public security agency will go greet your family,” he wrote on a WeChat group of 300 Berklee students from the class of 2024, the Justice Department said.

The charge of stalking carries a sentence of up to five years in prison, three years of supervised release and a fine of up to US$250,000.

The Chinese embassy in Washington did not immediately respond to a request for comment.

According to the charging documents, Wu also asked others to find out where the victim was living and posted her email address online in the hope that others would join in harassing her.

“Anyone who has the authority to check or is willing to do so, we would greatly appreciate it,” Wu posted in the university WeChat group.

US Attorney Rachel S. Rollins said in a statement that the department was alleging that Wu’s “threatening and harassing behaviour” did not amount to free speech. “Rather, it was an attempt to silence and intimidate the activist’s expressed views dissenting of the PRC.”

“Freedom of speech is a constitutional right here in the United States and we will protect and defend it at all costs,” Rollins added.

FBI agents said they believed Wu had succeeded in reporting the victim’s actions to Chinese authorities so they would investigate her and her family.

“This alleged conduct is incredibly disturbing,” said Joseph Bonavolonta, a special agent in the FBI’s Boston division.

Wednesday’s announcement follows a string of similar moves against mainland Chinese individuals for alleged harassment, a topic detailed in an annual report released last month by the Congressional-Executive Commission on China, an influential advisory body.

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Beijing has “continued a multi-year campaign of transnational repression against critics, Uygurs, and others to stifle criticism and enhance control over emigrant and diaspora communities”, the report said.

Andrew Kirk, the FBI special agent who investigated Wu’s case announced Wednesday, said in an affidavit that Wu admitted sending and posting the messages to frighten the victim.

Wu’s Instagram account, which according to court documents is “aldimeowu”, included images of a young Chinese man with glasses playing the guitar and the cello, holding a large grey cat and posing near the water at sunset.

The profile suggested he was from Beijing and liked jazz. And the last WeChat posting attributed to him, which contained many of the same images as Instagram, was dated three days before his arrest.

Kirk said in the affidavit that Wu hoped others would “abuse” her online, had no sympathy for her because what she did was a serious crime in China that betrayed her country and that she “does not deserve to be Chinese”.

Last year, a US federal court also accused a Chinese prosecutor of travelling to America, working with eight other individuals to direct a harassment campaign against a US resident and his family, and then ordering the destruction of evidence.

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Chinese officials have repeatedly said they advise all Chinese citizens to follow local laws abroad, adding that overseas outposts are not doing anything improper.

“Chinese public security authorities strictly observe the international law and fully respect the judicial sovereignty of other countries,” Foreign Ministry spokeswoman Mao Ning said in October at a regular briefing in Beijing.

Additional reporting by Orange Wang