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.

Buried in the trove of Executive Orders signed by President Donald Trump in his first weeks in office was a directive linked to last year’s campus protests over the Israel-Gaza war.