A pro-Palestinian graduate student at Columbia University, Mahmoud Khalil, has been arrested and detained by ICE ahead of a scheduled appearance with a federal immigration judge. Khalil, who was the lead student negotiator for the pro-Palestinian encampment at the university last year, was arrested at his university-owned home by agents with the Department of Homeland Security. His student visa and green card were reportedly subject to a revocation order by the State Department. Activists are calling for his release and have started an online petition with over 52,000 signatures.