Immigration officials arrested a former Columbia University student who helped to lead pro-Palestinian protests last spring, the Associated Press reported.

Mahmoud Khalil was taken into custody at his university-owned apartment in New York City, his attorney told the AP. Officials reportedly told Khalil that the State Department had revoked his student visa and green card. Khalil graduated in December. 

The Trump administration has pledged to deport what it deems pro-Hamas activists holding student visas, and the State Department is reportedly using artificial intelligence to review the social media accounts of student visa holders in order to identify international students who appear to support Hamas. The arrest of Khalil appears to be the first time the administration has followed through on the threat to arrest and deport students who participate in protests against Israel. 

When Columbia students set up an encampment on a university lawn last spring, Khalil served as the lead negotiator in talks with the university to end the demonstration.

Khalil’s lawyer told the AP that the immigration officers didn’t say why he was detained. The arrest also comes after the Trump administration changed policy to allow for immigration actions on college campuses and other areas previously considered “sensitive,” including churches and K-12 schools.

Columbia officials said in a statement that “law enforcement must have a judicial warrant to enter non-public university areas, including residential University buildings,” and that the university is “committed to complying with all legal obligations and supporting our student body and campus community.”