President Donald Trump touted the arrest of Mahmoud Khalil, the Columbia University graduate student and Palestinian activist detained by Immigration and Customs Enforcement over the weekend — signaling a larger campaign to punish anti-Israel protesters on college campuses.

Agents told Mahmoud Khalil’s attorney that they were revoking Khalil’s green card. He is legally considered a permanent resident.

Mahmoud Khalil, a recent Columbia graduate and Palestinian who is in the country legally and holds a green card, was arrested by ICE over his role in pro-Palestinian activism.