Rubio’s letter notified DHS that he had revoked both targets’ visas, setting in motion plans for U.S. Immigration and Customs Enforcement to arrest and attempt to deport them, according to a senior DHS official and another U.S. official who spoke on condition of anonymity to describe how the operation against Khalil took shape.

A New York federal judge is set to hear pivotal questions in the case of Mahmoud Khalil, a leader of large Gaza solidarity protests at Columbia University who now faces deportation after his arrest by Immigration and Customs Enforcement agents.