Who is Mahmoud Khalil, the Columbia student activist arrested by ICE?

A U.S. green card holder faces deportation after helping lead student protests at Columbia University in New York last spring over the war in Gaza. President Donald Trump has warned that Mahmoud Khalil's arrest is the “first arrest of many” as his administration cracks down on opposition to the war. But a federal judge has temporarily blocked his expulsion from the country, pending a Wednesday hearing in Manhattan federal court. Khalil was detained Saturday and is being held at a federal facility in Louisiana. He served as a student negotiator and was one of the most visible activists during the protests at Columbia, which also took place on other college campuses around the world.