The Trump administration on Thursday revoked Harvard University’s ability to enroll international students, marking a sharp escalation in the battle over the Ivy League school’s autonomy in the face of the administration’s policy demands.

“Harvard can no longer enroll foreign students and existing foreign students must transfer or lose their legal status,” the US Department of Homeland Security said in a statement.

Homeland Security Secretary Kristi Noem ordered her department to terminate Harvard’s Student and Exchange Visitor Program certification, citing the university’s refusal to turn over the conduct records of foreign students requested by the DHS last month.

Noem, in a letter to Harvard on Thursday, accused the university of “perpetuating an unsafe campus environment that is hostile to Jewish students, promotes-pro-Hamas sympathies, and employs racist ‘diversity, equity and inclusion’ practices.”

“Let this serve as a warning to all universities and academic institutions across the country,” the Homeland Security statement said.

Harvard has become ground zero for the Trump administration’s clash with elite US universities as it seeks to influence some campus programming, policies, hiring and admissions by threatening to cut off federal benefits. Trump officials say they are trying to banish antisemitism following contentious campus protests over the Israel-Hamas war and root out DEI practices they decry as “illegal and immoral discrimination.”

Harvard swiftly condemned the move as “unlawful” in a statement Thursday, adding it is “fully committed to maintaining Harvard’s ability to host international students and scholars, who hail from more than 140 countries and enrich the University – and this nation – immeasurably.”

“We are working quickly to provide guidance and support to members of our community. This retaliatory action threatens serious harm to the Harvard community and our country, and undermines Harvard’s academic and research mission,” university spokesperson Jason Newton said.

A substantial portion of Harvard’s student body could be impacted. The university says it has 9,970 people in its international academic population, and data shows 6,793 international students comprise 27.2% of its enrollment in the 2024-25 academic year.

Some Harvard staff worry draining the university of its foreign students would debilitate the academic prowess of both the institution and, potentially, American academia as a whole.

Harvard economics professor and former Obama administration official Jason Furman called the measure “horrendous on every level.”

“It is impossible to imagine Harvard without our amazing international students. They are a huge benefit to everyone here, to innovation and the United States more broadly,” Furman said. “Higher education is one of America’s great exports and a key source of our soft power. I hope this is stopped quickly before the damage gets any worse.”

This is a developing story and will be updated.

CNN’s Andy Rose and Matt Egan contributed to this report.