It was about 8:45 p.m. in Brooklyn on Wednesday, 45 minutes past the city’s curfew, when a peaceful protest march encountered a line of riot police, near Cadman Plaza.
Hundreds of demonstrators stood there for 10 minutes, chanting, arms raised, until their leaders decided to turn the group around and leave the area.
What they had not seen was that riot police had flooded the plaza behind them, engaging in a law enforcement tactic called kettling, which involves encircling protesters so that they have no way to exit from a park, city block or other public space, and then charging them and making arrests.
For the next 20 minutes in Downtown Brooklyn, officers swinging batons turned a demonstration that had been largely peaceful into a scene of chaos.
The kettling operations carried out by the city’s police after curfew on recent nights have become among the most unsettling symbols of the department’s use of force against peaceful protests, which has touched off a fierce backlash against Mayor Bill de Blasio and the police commissioner, Dermot F. Shea.
In the past several days, New York Times journalists covering the protests have seen officers repeatedly charge at demonstrators after curfew with seemingly little provocation, shoving them onto sidewalks, striking them with batons and using other aggressive tactics.
The escalation in the use of force in New York is part of a national trend. Across the country, local police have resorted to violent tactics to control the protest movement that was ignited by the death George Floyd, a black man, as he was being held down by a white officer in Minneapolis.
The strategy has been broadly defended by both Mr. de Blasio and Mr. Shea, who said it was necessary escalation to deter looters who ransacked parts of Manhattan over the weekend. “There comes a point where enough is enough,” Mr. de Blasio said on Thursday.
But there have been few reports of looting in the last three days of unrest. Instead, the police are deploying their aggressive tactics against protesters who have done little beyond violating the city’s 8 p.m. curfew to march. About 270 people were arrested on Thursday night.
As images of police officers using force to arrest seemingly peaceful demonstrators circulated online, Mr. de Blasio, who ran on a platform to reform the police, came under fierce criticism from some elected officials, community leaders and even his former aides. He was jeered and booed at a memorial for Mr. Floyd on Thursday.
By Friday, after more than a week of protests, the mayor had softened his tone, pledging to review reports of police officers behaving inappropriately and promising he would announce disciplinary measures against some officers shortly.
Later, in an interview on WNYC, the mayor said the encircling of protesters was sometimes necessary for public safety. “I don’t want to see protesters hemmed in if they don’t need to be,” he said, but he added “that sometimes there’s a legitimate problem and it’s not visible to protesters.”
On Thursday, the police commissioner said some police officers could be suspended if their behavior is found to have violated department standards. But he also said the anti-police rhetoric of the protesters and some elected officials who support them was putting officers in danger and he pointed to numerous instances in which the police had been injured with flying debris. “We need healing,” Mr. Shea said. “We need dialogue. We need peace.”
For many protesters, however, the aggressive tactics of the police to enforce the curfew have only worsened the crisis.
Axel Hernandez, 30, was protesting at Cadman Plaza on Wednesday night when police rushed into the crowd. Mr. Hernandez, who had marched several times this week, said it was one of the most peaceful demonstrations he had attended until the police charged in.
“That was the most peaceful, no bottles thrown, no anything,” he said. “The next thing I know, police rush in, with batons, and started moving people, and start hitting people.”
The kettle is a crowd control technique that has been used for decades. In theory, officers surround protesters and give them no exit, tire them out, then let them disperse in small groups.
But in New York in recent days, the maneuver has often ended with a charge and mass arrests. Since the city put a curfew in place this week, the police have used the technique in Brooklyn, Manhattan, and the Bronx.
According to accounts from Times journalists, other witnesses, and protesters who were arrested, many demonstrators have been trapped in kettle formations by the police and have had no way to disperse. In one instance, in Manhattan, police refused to let compliant protesters leave the area and comply with their orders.
“We were asking them, ‘Where should we go?’ Everyone’s hands were in the air,” said Lucas Zwirner, one of the protesters arrested on Wednesday after being surrounded by police officers in Manhattan after curfew. Many demonstrators told the police they would disperse and go home, Mr. Zwirner said, but officers would not let them through.
Police officers have used the maneuver to end some marches but not others. In Brooklyn on Wednesday, the police waited until 9 p.m. — an hour beyond the 8 p.m. curfew — to surround protesters and charge.
The day before, they allowed thousands to march peacefully across the Manhattan Bridge hours after curfew had ended, and escorted a group of thousands back to Brooklyn to disperse. In the Bronx on Thursday, officers began surrounding a group of demonstrators before 8 p.m., and began making arrests by 8:02 p.m.
“We are continuing to exercise discretion,” Mr. Shea said on Thursday evening. “Where we have made arrests, we have made them strategically.”