The takeover by protesters at Columbia came hours after the university said it had begun suspending students who had defied a directive to voluntarily disperse from an encampment that has occupied the main lawn for weeks.

By Tuesday evening (Wednesday AEST),police in riot gear had mobilised around the highly barricaded university and faced off with a growing swell of protesters who had come from across the city to show their support for those inside.

Roads were blocked off,train lines were diverted to pass the college and Columbia’s emergency management operation team issued a “shelter in place” alert urging people to avoid the area.

Then,just before 9.30pm,riot police carrying shields entered Hamilton Hall – a building that was occupied by students throughout the Vietnam War – using a ladder attached to an emergency services vehicle.

Members of the public yelled “Shame on you” as they watched on from the road below. People were eventually led out of the university and into law enforcement buses parked nearby,with their hands bound in zip ties.

Within three hours the campus had been cleared of protesters,said a police spokesperson,adding “dozens” of arrests had been made. Columbia University president Minouche Shafik released a letter in which she requested police stay on campus until at least May 17 – two days after graduation – “to maintain order and ensure that encampments are not re-established”.

The raid was the culmination of weeks of tension at Columbia,which began on April 17 when students set up the first encampment. They demanded the university sever ties to Israel,including the divestment of investments that support weapons manufacturing and an end to a dual-degree program in Tel Aviv.

Amid growing pressure from Congress over a rise in antisemitism on college campuses,Shafik – a former deputy governor of the Bank of England – called in police that day to break up the encampment.

Since then,encampments and protests have sprung up at dozens of institutions from coast to coast,resulting in the arrests and suspensions of hundreds of students at college campuses such as Yale University,the University of Southern California and Texas State University.

Maryam Alwan was one of the students arrested at Columbia when Shafik called in the authorities in mid-April.

The 22-year-old said she knew there would be risks involved in protesting,“but it was still a shock to be carried out in zip ties,quite literally by my own university,for setting up tents and calling for an end to genocide”.

“My wrists had cut off circulation,I had bruising afterwards,” Alwan said. “They denied us water,and we were in there[detained] for about eight hours just because of the sheer volume of people they had to process.

“But even as I say this,I don’t regret it. What the people of Palestine are experiencing is so much worse.”

Other students,however,took a different view. One graduate,who did not wish to be named for fear of being targeted,said she felt uncomfortable with some of the contested slogans protesters used,such as “From the river to the sea,Palestine will be free”.

Another expressed frustration when he was not allowed to enter the campus because it had been locked down to everyone but students who lived inside any of Columbia’s seven dormitories.

‘It’s gonna be bad’

Outside the university at lunchtime on Tuesday,pro-Palestine demonstrators called for an “intifida” (uprising) – a term President Joe Biden has condemned as hate speech. A small group of pro-Israel supporters stood nearby,with barricades separating the two groups.

Among them was actor and comedian Michael Rapaport,who is Jewish and grew up on Manhattan’s Upper East Side.

“Just like I said on January 6[the day of the 2021 Capitol riots],they need to start arresting people,” he told this masthead.

“All these universities have failed,and the long-term effects of this – for Jewish people,for free thinking,for antisemitism – it’s gonna be bad.”

The issue has also become a political powder keg for Biden as Republicans seize on the issue ahead of the presidential election in November.

Speaking to reporters at his hush-money trial on the other side of the city,former president Donald Trump decried the unrest on university campuses across America,describing them as “the Biden protests”.

He also later joined his party colleagues in calling for Shafik’s resignation.

“The Biden protests that are going on are horrible,” Trump said. “He’s got to get out and make a statement because the colleges are being overrun in this country.”

Biden has not commented on the protest,however White House spokesman Andrew Bates put out a statement saying the president “respects the right to free expression,but protests must be peaceful and lawful”.

– With agencies

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