When protests over the Israel-Hamas war took root on Columbia University's campus last spring, Mahmoud Khalil became a familiar, outspoken figure in a student movement that soon spread to other U.S. colleges.

The international-affairs graduate student was a fixture in and around the protest encampment on Columbia's Manhattan campus, serving as a spokesperson and negotiator for demonstrators who deplored Israel's military campaign in Gaza and pressed the Ivy League school to cut financial ties with Israel and companies that supported the war.