The arrest of a Palestinian activist who helped organize campus protests of the war in Gaza has sparked questions about whether foreign students and green card holders are protected against being deported from the U.

Immigration and Customs Enforcement agents told Mahmoud Khalil that his student visa had been revoked before his arrest.

Mahmoud Khalil, a prominent Palestinian activist who helped lead Columbia University’s student protest movement demanding a ceasefire in Gaza, was arrested Saturday night by federal immigration authorities,