President Donald Trump threatened to send troops to cities across the U.S. where thousands of protesters have taken to the street — some for as many as seven days — to demand justice in the killing of George Floyd and a long list of other unarmed black Americans who came before him.

Trump said Monday he will take action if local leaders are unable to stop the looting and destruction that we have seen come out of the protests in several cities, including Boston.

But former Massachusetts public safety secretary and Suffolk County Sheriff Andrea Cabral said that most people have been demonstrating peacefully.

“I think there's a great deal of evidence that ... it was an organized effort across the country by white nationalists to infiltrate these protests and to start this,” she said. “There were many, many, many instances where the police instigated the violence into an otherwise peaceful protest and immediately went to tear gas and immediately went to arresting people and beating people.”

Cabral told Jim Braude on WGBH News’ Greater Boston Monday that the media, too, has focused primarily on the violent minority at the protest, overshadowing the main message of the movement in the process.

“The protests are being defined by looting. They weren't defined by looting. They were defined by the number of peaceful protests that got no coverage,” she said.

But the chair of the NAACP’s Advocacy and Policy Committee Michael Curry, who joined Cabral on Greater Boston, said he understands why protesters may be driven to riot.

“I felt like throwing chairs and something through a window. I don’t think that’s abnormal. I think that’s normal. It’s as American as apple pie … you go through our history and you can see white males using protesting and mobs and riots,” Curry explained. “In fact, the NAACP was born out of a riot.”

"Don’t be surprised that if you ignore people’s oppression. If you ignore their pleas to address their grievances and you kill them. Do not be surprised if it does result in violence,” he added.

Many of the deaths that preceded Floyd’s — who died last week in Minneapolis after a police officer knelt on his neck for more than eight minutes — sparked widespread demonstrations, too.

That's why Cabral is hesitant to expect any substantive change will come out this.

“The fact that we’ve had this conversation as many times as we’ve had it indicates to me that, while there is a possibility that there will be some policy-based change going forward and that there may be other changes, it is entirely possible to me that there will not be," she said. "And that has much more to do with the basic infrastructure that protects at all costs the system that allowed George Floyd to be killed."

Curry, who previously served as the president of the Boston branch of the NAACP, agreed.

“I thought that when Tamir Rice was murdered when that 12-year-old boy was shot in a park in Cleveland that that would be a tipping point. I thought every white person in this country could see a 12-year-old boy playing with a toy gun like we all did and say that that would be a movement and a change. And it didn’t,” Curry said. “We need white Americans to step up.”

Cabral said we will continue to see the same cycle of violence and inaction until all Americans recognize and understand the country’s history of systemic racism.

“We keep having the same conversation over and over and over again because people use them as one-offs. ‘It's that particular officer. It's just a few bad apples.’ It is not. It is institutionalized terrorism of black people, which has been happening since slavery, but mostly since reconstruction, when the prospect of freed blacks was terrifying to white people in this country.”