NEW YORK -- Columbia University vowed to expel protesters who occupied a building on the New York college's grounds Tuesday as universities nationwide grapple with intensifying campus demonstrations against the Israel-Hamas war.

More than 1,000 protesters have been arrested on campuses in states including Texas, Utah, Virginia, North Carolina, New Mexico, Connecticut and New Jersey in recent days, some after violent clashes with police in riot gear.

The White House condemned the standoffs at Columbia and California State Polytechnic University, Humboldt, where protesters had occupied two buildings until officers with batons intervened overnight and arrested 25 people. Officials estimated the northern California campus' total damage to be upwards of $1 million.

President Joe Biden believes students occupying an academic building is “absolutely the wrong approach,” and “not an example of peaceful protest,” said National Security Council spokesperson John Kirby.

New York City Mayor Eric Adams claimed Tuesday that the Columbia protests have been “co-opted by professional outside agitators." The mayor didn’t provide specific evidence to back up that contention, which was disputed by protest organizers and participants.

“Walk away from this situation now and continue your advocacy through other means,” Adams advised the protesters. “This must end now.”

Other colleges have sought to negotiate agreements with the demonstrators in the hopes of having peaceful commencement ceremonies. As cease-fire negotiations appeared to gain steam, it wasn’t clear whether those talks would inspire an easing of protests.

Northwestern University notched a rare win when officials said they reached a compromise with students and faculty who represent the majority of protesters on its campus near Chicago to allow peaceful demonstrations through the end of spring classes.

The nationwide campus protests began at Columbia in response to Israel’s offensive in Gaza after Hamas launched a deadly attack on southern Israel on Oct. 7. Militants killed about 1,200 people, most of them civilians, and took roughly 250 hostages. Vowing to stamp out Hamas, Israel has killed more than 34,000 Palestinians in the Gaza Strip, according to the local health ministry.

Israel and its supporters have branded the university protests as antisemitic, while Israel’s critics say it uses those allegations to silence opposition. Although some protesters have been caught on camera making antisemitic remarks or violent threats, organizers of the protests, some of whom are Jewish, say it is a peaceful movement aimed at defending Palestinian rights and protesting the war.

On Columbia's campus, protesters locked arms early Tuesday and carried furniture and metal barricades to Hamilton Hall, among several buildings that were occupied during a 1968 civil rights and anti-Vietnam War protest. Demonstrators called the building Hind’s Hall, honoring a young girl who was killed in Gaza under Israeli fire.

Despite the chaos overnight, NYPD brass said Tuesday that officers won’t enter Columbia’s campus without the college administration’s request or an imminent emergency.

The takeover came hours after protesters had shrugged off an earlier ultimatum to abandon a tent encampment Monday or be suspended — restricted from all academic and recreational spaces, allowed only to enter their residences, and, for seniors, ineligible to graduate.

Mahmoud Khalil, a lead negotiator before talks with the administration broke down over the weekend, was among the suspended students. His suspension letter — which he shared with The Associated Press — said he had refused to leave the encampment after prior warnings, but Khalil said he had abided by the university’s demand to vacate the encampment on the campus lawn by the Monday afternoon deadline.

Columbia spokesperson Ben Chang said in a statement that anyone occupying Hamilton Hall risked being expelled from the university for escalating the protest “to an untenable situation — vandalizing property, breaking doors and windows, and blockading entrances.”

A CU Apartheid Divest spokesperson who declined to give her name Tuesday said she had been suspended and is not allowed back on campus. While she said she was not a representative for the demonstrators who had seized Hamilton Hall, she said other protesters’ commitment wouldn’t waver despite the risk to their educations and careers.

“We are willing to take on an extremely minor amount of risk compared to what the heroic people of Gaza are dealing with every single day,” she said.

Occupying protesters have insisted they will remain in Hamilton Hall until the university agrees to three demands — divestment, financial transparency and amnesty — even as Columbia administrators threatened repercussions from suspension to expulsion.

Ilana Lewkovitch, a self-described “leftist Zionist” student at Columbia, said it’s been hard to concentrate on school for weeks, amid calls for Zionists to die or leave campus. Her exams have been punctuated with chants of “say it loud, say it clear, we want Zionists out of here” in the background, she said.

Lewkovitch, who identifies as Jewish and studied at Columbia’s Tel Aviv campus, said she wished the current pro-Palestinian protests were more open to people like her who criticize Israel’s war policies but believe there should be an Israeli state.

While people involved in the Columbia demonstrations acknowledge that some people not part of the university community have participated, they forcefully disputed Adams’ allegation that outsiders are driving or unduly influencing the protests.

Numerous students and faculty who have spoken to the AP say the protests are student-led and that the great majority of people participating in them are students.

NYPD officials made similar claims about “outside agitators” during the huge, grassroots demonstrations against racial injustice that erupted across the city after the death of George Floyd in 2020. In some instances, top police officials falsely labeled peaceful marches organized by well-known neighborhood activists as the work of violent extremists.

Mattise reported from Nashville, Tenn. Associated Press journalists around the country contributed to this report, including Karen Matthews, Jim Vertuno, Hannah Schoenbaum, Sarah Brumfield, Stefanie Dazio, Christopher Weber, Carolyn Thompson, Dave Collins, Makiya Seminera, Philip Marcelo and Corey Williams.

This story has been corrected to show that Columbia University has not canceled its main graduation event.

Correction:

This story has been corrected to show that Columbia University has not cancelled its main graduation event.