Columbia University is restricting access to its Manhattan campus to only those who have school IDs as part of a new fall policy to deal with the possible return of unruly anti-Israel protesters.

After relaxing its color-coded threat-monitoring system to its lowest level, green, and allowing the school to be open to all this summer, Columbia will raise its threat level to orange and only allow students and staff on the Morningside campus starting Monday.

“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 University’s chief operating officer, Cas Holloway, said in a notice to the community over the weekend.

“We are particularly concerned about non-affiliates who may not have the best interests of the Columbia community in mind,” said Holloway, whose home was the target of anti-Israel vandals last week.

While guests will still be allowed on campus, they must now go through a new registration process implemented in June as well as present a government-issued ID.

The university has limited its entry points to five locations around the campus, including three on 116th Street, one on 114th Street, and one on 120th Street.

Officials said the new rules will remain in effect until further notice.

The security crackdown comes after anti-Israel vandals drew Hamas-themed graffiti, dumped paint and unleashed live crickets and mealworms across Holloway’s Brooklyn apartment building early Thursday.

The culprits spray-painted two inverted circles on the doorway, police said, a symbol that has been used in the past by Hamas to identify Israeli military targets.

Before fleeing, the vandals plastered threatening posters on the outside of the building that included the Ivy League executive’s name and photo as they criticized his handling of the violent anti-Israel protests that plagued Columbia’s Morningside Heights campus earlier this year.

The campus became the focal point for rampant protests against the war in Gaza that inspired similar demonstrations across the US. Columbia students set up encampments and took over historic Hamilton Hall, eventually clashing with cops.

During the demonstrations and the aftermath, the university garnered major backlash over its handling of the situation.

The protests also saw hundreds of people arrested and many charged with breaking into and occupying Hamilton Hall, though most of the cases were later dismissed.

It remains to be seen if the protests that ceased after the end of the spring semester will resume once students return to class Sept. 3.