Police carried out pre-dawn swoops Friday on students protesting the war in Gaza at two prestigious US universities, in the latest unrest on campuses across the country.
And late Thursday, police broke up a pro-Palestinian protest at the University of Calgary in western Canada using tear gas.
The police action at the Massachusetts Institute of Technology (MIT) near Boston in the northeast resulted in around 10 arrests, according to university president Sally Kornbluth, who said she had "no choice" but to dismantle the "high-risk flashpoint."
At the University of Pennsylvania in Philadelphia, officers in tactical gear forcibly removed several dozen students who had linked arms around a statue of Benjamin Franklin, NBC reported. It said they had been given two minutes to leave.
Students did not resist arrest at either US university and both of those actions appeared to have been relatively peaceful.
The demonstrations have spread to campuses abroad. The clash in Canada's Alberta province pitted police in tactical gear against about 150 students at the University of Calgary. It was not immediately clear how many arrests were made, if any.
At MIT, Kornbluth offered a timeline of the weeks of protest and negotiations on the campus, culminating in four warnings to students and finally her decision to ask police to clear the encampment, which she described as a "last resort."
For the demonstrators, she wrote, the encampment "symbolized a moral commitment that trumped all other considerations, because of the immense suffering in Gaza."
But for those supporting Israel, it "delivered a constant assertion, through its signs and chants, that those who believe that Israel has a right to exist are unwelcome at MIT.
"As a result, the encampment became a flashpoint."
She said those students who refused to leave were escorted "calmly" off campus before being placed under arrest.
But student organizers remained defiant and scheduled an "emergency rally" Friday at 3:00 pm (1900 GMT) to protest what they said was the university's "unjust discipline, eviction & arrest."
"You cannot suspend the movement. We will be back," a protest coalition wrote on Instagram.
Police have arrested more than 2,000 people nationwide in the weeks of US campus unrest.
Students have been protesting Israel's war against the Palestinian militant group Hamas in Gaza, and demanding that their schools divest financially from US weapons manufacturers and Israeli entities.
Campus authorities have sought to support the right to protest while acting against complaints of anti-Semitism and hate speech at the demonstrations.
In at least one incident, counter-protesters physically attacked demonstrators at the University of California, Los Angeles.
Some schools have struck deals with the students who have disbanded their encampments.
Other campuses have called in police, with striking images of officers clashing with students helping to turn the protests into a political issue ahead of the US presidential elections in November.
President Joe Biden last week defended the students' right to protest, saying that "dissent is essential for democracy," but adding that "order must prevail."
Donald Trump, Biden's presumptive Republican rival in November, has taken a tougher stance, dismissing the protesters as "radical left lunatics" and saying "they've got to be stopped."