The University of Southern California's University Park campus has reopened Sunday after a pro-Palestinian tent encampment was cleared out and dismantled, the university said.

All students, faculty and staff must present valid identification, USC said.

New York City Mayor Eric Adams on Sunday defended the police crackdown on college campus protests that have broken out in America's largest city.

"When those protests reach the point of violence, we have to ensure that we use a minimum amount of force to terminate what is perceived to be a threat," " Adams told ABC News "This Week" co-anchor Jonathan Karl.

Adams added that the police intervention resulted from days of communication between the police and school officials.

"We knew we had to get permission unless there's imminent threat to life, or severe threat to property," he said, adding, "We were not going to overstep our legal authority."

When pressed by Karl about criticism, including from some other Democrats, that the response to protesters was disproportionate given that they were largely nonviolent, Adams said, "One has the right to have his or her opinion, and I respect that. ... And I have an obligation and responsibility to ensure the city is safe."

-ABC News' Kristina Abovyan

A pro-Palestinian tent encampment on the University of Southern California campus was cleared out and dismantled Sunday morning without any arrests being made, university officials said.

Joel Curran, a spokesperson for USC, said in a statement that the encampment, established by protesters 12 days ago, was "peacefully" taken down.

“Earlier today, the University of Southern California Department of Public Safety (DPS) successfully removed the illegal encampment rebuilt on the university’s campus. It was necessary to request the Los Angeles Police Department to respond to provide security as this was carried out peacefully," Curran said. "No arrests have been reported. We want to thank LAPD for assisting DPS in clearing the encampment and restoring normalcy for students and community as quickly and safely as possible. We will share more information with our community later today.”

-ABC News' Tristan Maglunog

The University of Southern California said the encampment at University Park Campus has been cleared and the campus remains closed.

Columbia University has released a statement addressing its authorization to allow the NYPD on campus, saying the decision was "made to restore safety and order to our community."

In its statement, the university said after they learned protesters had entered Hamilton Hall last night and "occupied, vandalized, and blockaded" it, they were left with "no choice" but to allow the police in. The university also said in a statement that they believe "that the group that broke into and occupied the building is led by individuals who are not affiliated with the University."

"Columbia public safety personnel were forced out of the building, and a member of our facilities team was threatened. We will not risk the safety of our community or the potential for further escalation," the university's statement continued.

The university said in its statement the NYPD's presence is about the "actions of the protestors, not the cause they are championing."

"We have made it clear that the life of campus cannot be endlessly interrupted by protesters who violate the rules and the law," the statement read.

-ABC News' Joshua Hoyos