WASHINGTON Protesters gathered Saturday outside US Immigration and Customs Enforcement (ICE) headquarters in Washington, DC to demand the release of Palestinian activist Mahmoud Khalil -- a green card holder and recent Columbia University graduate who helped organize campus protests last year. Demonstrators later took to the streets, chanting: “We want justice, you say how. Free Mahmoud Khalil now!” and “Free all the students today.” Many held banners that read: “Free Palestine”, “Release