NEW YORK — Columbia University is restricting access to campus as of Monday due to concerns about pro-Palestinian protests as the school year revs up.

The Morningside Heights campus, which had been open to everyone for most of the day over the summer, started requiring student or faculty identification for entry — nearly four months after police cleared a building occupation and encampment demanding Columbia divest from Israel.

“This change is intended to keep our community safe given reports of potential disruptions at Columbia and on college campuses across the country as we approach the beginning of the new school year,” Columbia Chief Operating Officer Cas Holloway said in a memo.

“We are particularly concerned about non-affiliates who may not have the best interests of the Columbia community in mind,” the email to students and faculty read.

Columbia started rolling out a color-coded campus lockdown system in early July, restricting access to only students living on campus when the status turns “red.” The last time the campus was regulated in that way was when university president Minouche Shafik summoned the NYPD, resulting in the arrests of more than 100 protesters, and in the weeks that followed. The majority of charges have since been dropped.

At the end of last week, the campus was open to all during the day while buildings were restricted, or “green,” but shifted to “orange” after 10 p.m., meaning students needed to show identification overnight.

As of Monday, the “orange” code is in effect at all times of day. Students and faculty can enter campus with IDs at five points around the perimeter of campus; all other entry points are closed. Only pre-authorized guests may receive exemptions.

“This status will remain in effect until further notice,” Holloway continued. “We will continuously assess the situation and adjust as necessary.”

The color-coded system facedpushback last week in the student newspaper, likening it to pandemic-era protocols that shuttered the campus.

Holloway’s apartment building in Brooklyn Heights was vandalized last week with red paint with vandals leaving a box of crickets and mealworms and breaking the glass of the lobby door with a hammer, police said. They also painted red inverted triangles on the building’s exterior, a controversial symbol of pro-Palestinian resistance that Hamas terrorists use to mark military targets.

“We’ve seen an explosion of antisemitism and there’s no excuse,” Mayor Adams said on X Friday. “I’m sorry to Cas Holloway for this vandalism. Hate has no place in our city.”

The NYPD’s Hate Crimes Task Force is investigating the matter, Adams said.

Classes at Columbia’s undergraduate college resume Sept. 3.