At least two anti-Israel protesters were arrested on Tuesday as masked demonstrators returned to Columbia University in New York City, ground zero for last semester’s most intense escalations.

On the first day of fall classes, a group of anti-Israel agitators splattered red paint all over the Columbia University Alma Mater statue, which was installed in 1903. Approximately 100 protesters stood outside a university entrance and chanted “Free Palestine” while calling for the school to divest from Israel, before moving outside Barnard College.