After the University of California, Berkeley, cancelled a speech by Breitbart Editor Milo Yiannopoulos due to violent protests on campus, President Donald Trump published a tweet threatening to revoke the school’s federal funding.

If U.C. Berkeley does not allow free speech and practices violence on innocent people with a different point of view – NO FEDERAL FUNDS? — Donald J. Trump (@realDonaldTrump) February 2, 2017

Yiannopoulos, an editor of Breitbart and outspoken member of the white nationalist “alt-right” movement, was scheduled to speak at University of California, Berkeley on Wednesday night.

However, his appearance prompted a large protest on campus, with 1,500 people out to oppose Yiannopoulos ahead of the event, according to the Los Angeles Times. Protesters threw metal barricades and broke windows, per the LA Times.

About two hours before Yiannopoulos was scheduled to speak, the university called off the event due to concerns about violence at the protest.

“Amid an apparently organized violent attack and destruction of property at UC Berkeley’s Martin Luther King Jr. Student Union, the UC Police Department (UCPD) determined it was necessary to evacuate controversial speaker Milo Yiannopoulos from campus and to cancel his scheduled 8 p.m. performance. Yiannopoulos had been invited by the Berkeley College Republicans,” the university said in a statement.

The school said that the “violence was instigated by a group of about 150 masked agitators who came onto campus and interrupted an otherwise non-violent protest.” According to the statement, protesters started fires, threw Molotov cocktails, and threw rocks and fireworks at police.

“Campus officials added that they regret that the threats and unlawful actions of a few have interfered with the exercise of First Amendment rights on a campus that is proud of its history and legacy as the home of the Free Speech Movement,” the university said in the statement.