National Security Advisor Robert O'Brien speaks to reporters outside of the West Wing of the White House in Washington, DC on…
FILE - National Security Advisor Robert O'Brien speaks to reporters outside of the West Wing of the White House in Washington, May 21, 2020.

WASHINGTON - U.S. national security adviser Robert O’Brien said Sunday that it was an “absolute outrage” that three policemen in Minneapolis, Minnesota, stood by and watched without intervening last week as another policeman pinned a black man to the street with a knee to his neck as he pleaded that he couldn’t breathe.

George Floyd, a 46-year-old African American man who was handcuffed and lying on the street after he was suspected of passing a counterfeit $20 bill, died in the incident last Monday. Derek Chauvin, the white policeman who held him down for minutes, was charged Friday with third degree murder in the case.

Video of the incident was aired widely on social media and network newscasts, sparking five days of protests in the United States in dozens of cities. The demonstrations have often erupted in chaos, with protesters setting police cars and government buildings afire and clashing with authorities in riot gear. Looters have ransacked stores and run off with high-priced consumer products.

This photo provided by the Ramsey County Sheriff's Office shows former Minneapolis police Officer Derek Chauvin, who was arrested Friday, May 29, 2020, in the Memorial Day death of George Floyd.

Chauvin and his three police colleagues at the scene were all fired from the city’s police force. The three policemen who watched the incident unfold are under investigation, but no charges have been filed against them.

“What were they thinking?” O’Brien asked on ABC News’ “This Week” show. O’Brien said he was not prejudging the case against the three former policemen, but said, "I can’t imagine they won’t be charged.”

O’Brien said the U.S. government mourns Floyd’s death and prays for the Floyd family.

“That should never have happened in America,” he said.

In an interview on CNN, O’Brien questioned why Chauvin, whom he called a “dirty cop,” was still on the Minneapolis police force at the time of the Floyd incident after multiple complaints had been filed against him in recent years.

“We love our law enforcement” in the U.S., O’Brien said. He rejected the suggestion there is “systemic racism” in U.S. police forces, while acknowledging that “there are some bad cops that need to be rooted out. We’ve got a few bad apples that give law enforcement a bad name. I think they are the minority.”

A person runs while a police vehicle is burning during a protest in Los Angeles, over the death of George Floyd, May 30, 2020.

Some U.S. authorities have blamed both far-left and far-right provocateurs for the violence in cities from coast to coast, some of the worst in the country since perhaps the days of extended protests against the U.S. involvement in the Vietnam War in the 1960s.

While O’Brien told ABC, “We’ll keep our eyes out for anyone,” he blamed the radical leftist group Antifa for the violence.

“This is Antifa, they’re crossing state lines,” to foment violence against police and destroy property, he said.

“This has to stop,” he said. “This Antifa violence has to stop.”

A top Democrat, House Speaker Nancy Pelosi, said she has been told 80% of those arrested in the protests in Minneapolis were not local residents, but came from other places outside Minnesota, an upper Midwestern state.

In the adjoining St. Paul, Minnesota, Mayor Melvin Carter told CNN it became obvious that some people rioting and looting in his city were “not driven by a love for our community."

O’Brien said on CNN, “Who know where they come from,” but vowed, “We’re going to get to the bottom of it.”

FILE - An Atlanta Police Department vehicle burns during a demonstration against police violence, May 29, 2020 in Atlanta.

Atlanta Mayor Keisha Lance Bottoms told CBS News’ “Face the Nation” show that some of the protesters in her southern city also were unknown to her.

“You know, I can't say who they are,” Bottoms said. “It looked differently racially in our city than our normal protests looked. And it was — it was just — it was a different group. So, we don't know who they were, but many of them were not locally based. I'll say that.”

O’Brien named four countries — China, Russia, Zimbabwe and Iran — that have cast the U.S. in unfavorable terms because of the death of Floyd and the ensuing violent demonstrations — all coming in the midst of the coronavirus pandemic and economic turmoil it has created. More than 40 million workers, about a quarter of the U.S. labor force, have been laid off.

But O’Brien said the U.S., where peaceful protests remain a bedrock of the nation’s democratic principles, is not like authoritarian countries where police often arrest even non-violent anti-government demonstrators.

“That’s what makes America different from other countries,” he said.

O’Brien said other countries casting aspersions on the U.S. “aren’t going to take advantage of us. We stand with the peaceful protesters. We want peaceful