Donald Trump has called detained Palestinian student activist Mahmoud Khalil 'anti-American' and has warned of further arrests. Khalil, a postgraduate student at Columbia University, was detained by federal immigration agents and is currently awaiting deportation proceedings. Trump accused Khalil of being a 'radical foreign pro-Hamas student' and stated that his arrest is the first of many to come. The Trump administration has not provided details about Khalil's case or the specific charges against him.