After nightfall, a unit of heavily armed American soldiers fanned out across the rooftop of an urban building and set up their defense perimeter. Clad in military fatigues and state-of-the-art tactical gear, they locked and loaded their AR-15-style rifles, then scanned the streets below for enemy targets.

"They light shit on fire, we can shoot on them, right?" one soldier asked.

"Yep," a colleague chirped.

"Well, very fucking well," the first one replied matter-of-factly. "Hopefully, they light shit on fire."

This real-life footage appears for the first time in Against All Enemies, a documentary, with funding from a Vermont-based organization, that will premiere in June at the Tribeca Festival in New York City. The scene was shot not in Fallujah, Kabul or another overseas war zone but in Louisville, Ky., in September 2020, during a street demonstration several months after the police shooting of Breonna Taylor. The rooftop "soldiers" weren't national guardsmen or police officers but members of the Oath Keepers, a far-right paramilitary group led by founder Stewart Rhodes.

"It's almost like we're in a foreign country doing a stability operation against an insurgency," Rhodes told the film's director, Charlie Sadoff, at the time. "That's the same kind of shit [these men] have been doing their whole career. But now they're doing it here within the United States."

In November, Rhodes was found guilty of seditious conspiracy and other crimes for his involvement in the January 6, 2021, insurrection in Washington, D.C. The former U.S. Army paratrooper and Yale Law School grad is believed to have recruited as many as 35,000 police officers, active U.S. service members and veterans to his anti-government militia. Though only slightly over 6 percent of all Americans have served in the military, approximately 15 percent of the more than 1,000 people charged with storming the U.S. Capitol to try to overturn the results of the 2020 presidential election have military or law enforcement backgrounds.

Vermonter Dan Barkhuff is deeply troubled by this disproportionate representation of American vets in the ranks of the January 6 insurrectionists. A former U.S. Navy SEAL who did multiple combat deployments in Iraq, Afghanistan and Africa, Barkhuff is an executive producer of Against All Enemies and founder and president of the South Burlington-based Veterans for Responsible Leadership. The political action committee raised nearly $200,000 to help get the documentary made and signed up many of its on-air participants.

Narrated by actor Peter Coyote, Against All Enemies features chilling footage and compelling interviews with military veterans and members of Congress who were in the Capitol building during the siege. It reveals how violent extremist groups such as the Oath Keepers, Proud Boys and Three Percenters offer veterans a sense of identity, camaraderie and mission that's often missing from their civilian lives. In turn, these veterans become "force multipliers," lending their legitimacy, organizational skills and lethal fighting power to domestic terror groups.

Barkhuff, 44, lives in South Burlington and works as an emergency medicine physician at the University of Vermont Medical Center. For the film's production, he enlisted the help of other veterans who are alarmed by the rise of violent extremist groups that target vets for recruitment. Like all U.S. service members, he noted, he swore an oath to "support and defend the Constitution of the United States against all enemies, foreign and domestic" — an oath that would be violated by taking up arms against fellow Americans.

"We're at an extremely risky time in American history," Barkhuff told Seven Days. "You've got this 20-year war [in Afghanistan], fought by volunteers who've been told for 20 years that they're special and doing God's work ... and [their] actions are true and just."

Once those soldiers leave the military, Barkhuff explained, many don't know what to do next. Without the sense of common purpose that combat provided, a small percentage get radicalized and bring the war home with them.

Barkhuff, formerly a traditional conservative, now describes himself as a "moderate Democrat." He's a gun owner who supports individual freedoms, the Constitution, smaller government and adherence to the rule of law. In 2020, he criticized then-president Donald Trump as a fake conservative in an ad produced by the Lincoln Project political action committee.

"I don't agree with Joe Biden on many issues," Barkhuff said in the ad. "But one thing we agree on is that we are a nation of laws, and the Constitution is a sacred document — a document that I fought for and some of my friends died for."

In October 2020, Barkhuff and other members of Veterans for Responsible Leadership were disturbed by the news that the Federal Bureau of Investigation had arrested 14 members of a far-right extremist group for plotting to kidnap and assassinate Gov. Gretchen Whitmer (D-Mich.). Many of those involved were former military.

After the January 6 attack, Barkhuff and other members of his group's board, including Kenneth Harbaugh, a retired U.S. Navy pilot, began talking about how they and other vets could counter this growing domestic terrorist threat. Harbaugh, one of the film's writers, used his connections in Washington, D.C., to line up interviews with members of Congress who were in the Capitol building that day. They include Rep. Mikie Sherrill (D-N.J.), a former U.S. Navy helicopter pilot; Rep. Jason Crow (D-Colo.), a former U.S. Army Ranger; and Rep. Seth Moulton (D-Mass.), a former U.S. Marine Corps officer.

"I often ask myself: How did I wind up on one side of that door [in Congress]," Moulton says in the film, "and my fellow veterans, who raised that same right hand and took that same oath, how did they wind up on the other side?"

Against All Enemies also features interviews with retired U.S. Army general Stanley McChrystal, who served as commander of the Joint Special Operations Command; and Denver Riggleman, a former U.S. Air Force officer who later served as an adviser to the January 6 commission. Interspersed with those interviews is footage shot by director Sadoff, who spent nearly a year embedded with the Oath Keepers during their training and field operations.

In addition to his fundraising, Barkhuff recruited Sebastian Junger to the project as an executive producer and adviser. The journalist, author and filmmaker, whose works include the best-selling 1997 book The Perfect Storm: A True Story of Men Against the Sea and the 2010 Academy Award-nominated documentary Restrepo, was "a natural intellectual ally for the film," Barkhuff said.

"You're in the military ... and you're part of this tribe, where you contribute to the tribe and protect the tribe and the tribe protects you," Barkhuff said, echoing a major theme of Junger's 2016 book Tribe: On Homecoming and Belonging. "That's this really powerful feeling. And it's being manipulated by domestic extremists."

Seeing the Proud Boys, Oath Keepers and Three Percenters at rallies in tactical gear and fatigues, it's tempting to dismiss them as posers, special ops wannabes who run around in the woods on weekends with military-style rifles to feel macho. Some members do fall into that "knucklehead" category, Barkhuff said. But he cautioned that many others are decorated, battle-hardened combat vets who are spoiling for a fight.

Barkhuff pointed to the recently closed paramilitary training facility in West Pawlet, known as Slate Ridge, as an example of this kind of extremism "coming home to roost" in Vermont. Earlier this month, Gov. Phil Scott signed legislation making such training facilities illegal.

But it's not the tactical training and combat expertise in these violent extremist groups that worry Barkhuff the most. It's the legitimacy and social cachet that veterans bring to them.

"If you're this impressionable young white male — and let's be honest, most of them are young white males — and you see somebody who did two tours in Iraq is a Proud Boy, that's where it matters," he said.

Part of the problem, Barkhuff continued, is the way in which society has lionized veterans and military service in recent decades. Much of this adulation was a reaction to the disrespect that was hurled at Vietnam vets upon their return home in the 1960s and '70s.

While appealing to young people's patriotism and their sense of duty and higher purpose can be a good thing, Barkhuff said, it has had unintended consequences. To get people to enlist and fight the country's wars, the military drums into new recruits' heads that they're exceptional and elite — a phenomenon he experienced firsthand as a Navy SEAL.

"You have so many people telling you you're special all the time. And in certain ways, you are," Barkhuff said. "The work is special. But it doesn't make you a 'special person' to have done the work."

Offering workable solutions to the current threat isn't the focus of Against All Enemies; the documentary devotes more screen time to tracing the historical roots of Christian white nationalism in many of these extremist groups. Among those featured prominently in the film, however, is someone who is pursuing solutions: Kristofer Goldsmith, an Iraq War veteran who became famous for infiltrating the white nationalist group Patriot Front. His organization, Task Force Butler Institute, tracks neo-Nazis to expose their fascist intentions.

As for Barkhuff, he believes all those who served in the military and swore the oath to support and defend the Constitution should speak out against these groups, which he sees as the greatest current threat to the nation's domestic security.

"We, meaning other veterans, are the only ones who can call them out," he said. The challenge is that many of these far-right extremists, including the Oath Keepers, believe that they're upholding the same vow.

"The scary part of all this stuff is, they think they're right ... with just as much conviction as I think I'm right," Barkhuff added. "And so how do you walk back from that?"

Corrected May 25, 9:12 a.m.: This story was updated to reflect Dan Barkhuff's current political affiliation.