Protesters toppled two statues of former US presidents in the western state of Oregon, prompting President Donald Trump to call Monday for the demonstrators to be locked up and for federal intervention.
"Put these animals in jail, now," Trump said in a series of tweets after learning of the statues of Theodore Roosevelt and Abraham Lincoln being felled Sunday night.
"The Radical Left only knows how to take advantage of very dumb 'leadership' fools," he added. "This is Biden! Law & Order!"
The protesters, estimated at about 300 by police, had gathered in the city of Portland -- the site of almost nightly anti-racism protests for more than four months -- for what was billed as an "Indigenous Peoples Day of Rage" ahead of Columbus Day on Monday.
Similar protests nationwide in recent months prompted by the death of George Floyd, an unarmed black man who died in police custody in Minneapolis, have led to statues of Confederate leaders and other US presidents linked to America's history with slavery being felled.
Police said the protesters in Portland on Sunday had marched to the Oregon Historical Society where they broke windows and lobbed three lit flares inside the building which caused little damage.
In a tweet, Trump said the demonstrators were "taking advantage of fools" and urged the city to "call in the Feds!"
Portland Mayor Ted Wheeler denounced the violence as "obscene," saying it had turned attention away from the symbolism of Columbus Day, which for Native people in the US is a painful reminder of oppression.
"It's unfortunate that yesterday, a group of individuals acting under what they described as the 'Indigenous Peoples' Day of Rage,' coopted what is otherwise a peaceful opportunity for education and reflection and celebration of the achievements and accomplishments of the Native American community and instead engaged in criminal acts," Wheeler told reporters.
Portland police chief Chuck Lovell said three people had been arrested in connection with the unrest.
He said the protesters had used a vehicle to first topple Roosevelt's statue before turning their attention to Lincoln's statue.
Statues of two other former presidents have previously been felled by protesters in Portland.
One was of Thomas Jefferson, who enslaved more than 600 people over the course of his life and another was of George Washington who also owned slaves.