US President Donald Trump has branded demonstrators who marched through Boston in opposition to a right-wing rally in the city as "anti-police agitators".
An estimated 15,000 protesters dwarfed the attendees of the curtailed right-wing, Free Speech rally on Saturday, which was eventually cut short.
Taking to Twitter, Mr Trump wrote: "Looks like many anti-police agitators in Boston. Police are looking tough and smart! Thank you."
He also hailed what he referred to as a "great job" done by law enforcement officers and the city's mayor.
The president may have reflected on his earlier inflammatory comments about anti-racism protesters, as he once again took to Twitter to applaud their stance against "bigotry and hate".
He added: "Our great country has been divided for decades. Sometimes you need protest in order to heal, & we will heal, & be stronger than ever before!"
The rally was held just one week after a car drove into a crowd of counter-protesters in Charlottesville killing 32-year-old Heather Heyer and injuring 19 others.
The counter-protesters in Virginia had been demonstrating against white supremacist groups' Unite The Right rally.
Mr Trump has been widely criticised for his apparent failure to single out white supremacists for condemnation in his initial responses to the violence.
Following the abandoned rally on Boston Common, police vans escorted the conservatives from the area, while some counter-protesters scuffled with armed officers who were keeping the two groups apart.
Organisers of the Free Speech rally, had publicly distanced themselves from the neo-Nazis, white supremacists and others who fomented violence in Charlottesville on August 12.
The Boston Free Speech Coalition, which organised the event, said it had nothing to do with white nationalism or racism, and added that its group is not affiliated with the Charlottesville rally organisers in any way.
"We are strictly about free speech," the group said on its Facebook page, "we denounce the politics of supremacy and violence."
In Boston, there were fears that white nationalists might attend the rally, raising the spectre of confrontation just seven days after Charlottesville.
Counter-protesters in the Massachusetts capital chanted anti-Nazi and anti-fascism slogans, and waved signs which read "Resist Fascism", "Hate Never Made US Great", and "Smash White Supremacy".
Footage from the rally showed counter-protesters chasing a man with a Trump campaign banner and cap, swearing and shouting at him.
However, other counter-protesters intervened and helped the man over a fence and into the area where the conservative rally was being staged.
The permit issued for the rally came with severe restrictions, including a ban on backpacks, sticks and anything that could be used as a weapon.
Boston's Democratic mayor, Marty Walsh, and Massachusetts' Republican governor, Charlie Baker, both warned that extremist unrest would not be tolerated in the city famed as the cradle of American liberty.