More than 100 students were arrested on Thursday after Columbia University called in the police to empty an encampment of pro-Palestinian demonstrators, fulfilling a vow to Congress by the school’s president that she was prepared to punish people for unauthorized protests.

“I took this extraordinary step because these are extraordinary circumstances,” the president, Nemat Shafik, wrote in a campuswide email on Thursday afternoon.

The president’s decision swiftly sharpened tensions on campus, which has been battered for months by boisterous pro-Palestinian demonstrations that many Jewish people regarded as antisemitic. And it stood to become a milestone for the country, as campuses have been torn by the Israel-Hamas war and grappled with how to manage protests.

What was far less clear was whether the harsher tactics would form an updated playbook for officials struggling to calm restive campuses, or do little besides infuriate and inflame.

Protesters had already promised that any effort to dismantle the encampment would only embolden them.

Dr. Shafik’s message arrived as swarms of New York City police officers, clad in riot gear and bearing zip ties, marched on the encampment of about 50 tents that had sprung up earlier in the week. On Thursday, protesters clutched Palestinian flags, demonstrators sat huddled on the ground and a thicket of onlookers kept watch as officers bore down on tents in the zone that had styled itself as the “Gaza Solidarity Encampment.”

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