Justin and his buddies look like they're from a special ops team: They're wearing military-style vests and carrying rifles and pistols. But they aren't military, and they aren't police.

"I see myself as a concerned citizen who happens to be armed," he says.

They won't give their last names, citing safety and job security. But on a recent evening they are standing watch over about 200 protesters at a rally about the death of George Floyd in Missoula, Mont.

They say they're there to keep things peaceful. Missoula hasn't seen any rioting or looting associated with a week's worth of protests, but if some people incite violence, the men plan to enter the crowd and grab them. They carry handguns and other weapons in case someone starts shooting, they say.

"I'm not going to bring fists to a gunfight, man," Justin says.

They say they want to protect demonstrators, but there are also rumors that busloads of antifa activists are coming to incite riots in small towns and cities across the country. That's why a man named Calvin is here holding an AR-15. He says he isn't a counterprotester.

"I'm not racist, I have zero problems with people protesting, and I support it 100%," he says. "But I don't support my town getting burned down."

Wyoming, Minnesota, Pennsylvania and other states have seen armed people responding to antifa rumors. But the rumors have been widely debunked.

"We have no credible intelligence that that is true," Missoula Police Chief Jaeson White said in a video posted to Twitter. "We firmly believe that it has been rumor and speculation."

But the rumors are having real consequences. Some organizers have canceled protests over the presence of armed men and women. On social media, people are posting photos of vans or school buses they believe are carrying antifa activists.

"We do see people sharing these messages out of fear," says Joan Donovan, an expert on media manipulation, online extremism and disinformation campaigns at Harvard University's John F. Kennedy School of Government. "The idea of an outside force coming in and invading your small town in particular does feel threatening."

However, antifa, a loose network of left-wing activists who sometimes violently confront fascists and white supremacists, is more of a movement than a well-oiled organization.

"Antifa operates as a designation similar to the way someone might describe themselves as a punk rocker," Donovan says.

Still, Donovan says there's been a lot of disinformation coming out about antifa in recent days, including from President Donald Trump and his attorney general, William Barr. Both assert the movement is behind the violence at rallies across the country, and Trump threatened to list antifa as a domestic terrorist organization.

NPR has reviewed court documents of 51 individuals facing federal charges in connection with the unrest. As of Tuesday morning, none is alleged to have links to the antifa movement.

"You also have a right-wing media ecosystem that is pushing this narrative," Donovan says.

On social media, Twitter has confirmed at least one white nationalist group created a fake antifa account to spread false rumors. Activists suspect there are several more. The origin of the rumor that busloads of antifa activists are coming to small towns and cities is still unclear, but armed people showing up at demonstrations such as the one in Missoula worry protesters such as Erin Giefer.

"The presence of guns and people who have a military get-up and camo swarming the area makes me feel unsafe," she says. "What if somebody does shoot, or one of these cars backfire and then someone starts shooting. That has far more potential for violence and recklessness than anything else."

A few organizers and protesters have said they welcome offers of protection. But the majority say they are deeply skeptical. They say they believe the people with guns are trying to hijack the narrative, trying to make protesters appear more dangerous than they are, or intimidate them from exercising their First Amendment rights.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado and KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by theCorporation for Public Broadcasting.

Copyright 2021 NPR. To see more, visit https://www.npr.org.