On Monday night, protesters again gathered in the streets of Ferguson, Mo. Demonstrations in the St. Louis suburb have flared up in recent days to mark the first anniversary of the death of Michael Brown, an unarmed black teenager who was fatally shot by a white police officer.

Also on the scene overnight: Members of a citizen militia group known as the Oath Keepers.

The men — all of them white and heavily armed — said they were in the area to protect someone who worked for the Web site Infowars.com, which is affiliated with talk-radio conspiracy theorist and self-described “thought criminal against Big Brother” Alex Jones.

Reporters and Black Lives Matter activists immediately took note.

“Media launches new demonization campaign as Oath Keepers arrive in Ferguson,” read an Infowars.com headline Tuesday; the story noted that Oath Keepers members were with two reporters for the site.

If the presence of this group was confusing, here’s a brief explainer on their background and history in Ferguson.

Who are the Oath Keepers?

On their Web site, the Oath Keepers are described as a group focused on fulfilling “the oath all military and police take to ‘defend the Constitution against all enemies, foreign and domestic.'” The site notes that the organization is composed of members who have, or have previously had, some sort of connection to law enforcement or the military.

The Southern Poverty Law Center, however, describes the Oath Keepers as a “fiercely antigovernment, militaristic group.”

“The core idea of the group is that its members vow to forever support the oaths they took on joining law enforcement or the military to defend the Constitution,” reads the SPLC site. “But just as central is the group’s list of 10 ‘Orders We Will Not Obey,’ a compendium of much-feared but entirely imaginary threats from the government — orders, for instance, to force Americans into concentration camps, confiscate their guns, or cooperate with foreign troops in the United States.”

One Oath Keeper named Sam Andrews told the New York Times last year that the group’s membership includes “a really broad group of citizens, and I’m sure their motivations are all different. In many of them, there’s probably a sense of patriotism. But I think in most of them, there’s probably something that they probably don’t even recognize: that we have a moral obligation to protect the weakest among us.”

As The Post’s Terrence McCoy wrote in November:

The Oath Keepers are many things to many people. For one fervent believer, it’s about the Constitution. For another, it’s about a .50-caliber Bushmaster and his right to carry it. Others talk of fear: fear America has become a security state. Fear President Obama has become a dictator. Fear the Oath Keepers are needed now more than ever — especially in Ferguson, Mo.

The group, McCoy added, “came into being after founder Stewart Rhodes wrote a 2008 manifesto calling for men and women to protect a complacent America besieged by what he described as dictatorial leaders. ‘If a police state comes to America, it will ultimately be in your hands,’ Rhodes, a Yale Law School graduate, wrote. ‘That is a harsh reality, but you had better come to terms with it now, and resolve to not let it happen on your watch.'”

What are the Oath Keepers doing in Ferguson?

Abby Phillip, who is on the the ground for The Washington Post in Ferguson, described the scene like this:

Members of the group arrived on West Florissant Avenue in Ferguson in the early morning as protests wound down just before 2 a.m.
The small group of men — dressed in military-style camouflage and bullet-proof vests, and armed with long guns — initially startled protesters, some of whom asked the Oath Keepers to leave. But they insisted that they were “on their side,” and had arrived to protect protesters from police, who stood standing watching in riot gear across the street. They said Missouri law permitted them to openly carry legally owned weapons.
When the Oath Keepers crossed to the same side of the street where police stood, protesters followed. But police didn’t react to their presence.

Here are a few pictures:

Where is it legal to openly carry a long gun?

Six states and the District of Columbia prohibit the open carrying of long guns. Another six set restrictions but don’t prohibit it. In every other state, including Missouri, it is legal to carry a loaded long gun in public without a permit, according to the Law Center to Prevent Gun Violence.

Has this group been in Ferguson before?

Yes, in November — though their presence was rather confusing for residents and activists then, too.

Here’s the St. Louis Post-Dispatch, describing the scene a few days after it was announced that Darren Wilson — the officer who shot Brown — wouldn’t face criminal charges:

Following a night of arson fires and bashed storefronts that hit close to home, Greg Hildebrand stood naked Tuesday, drying off from a needed shower, when he noticed somebody on the rooftop.
“I opened the window and said, ‘Hey, can I help you?’” said Hildebrand, 35, a website developer.
The man said he was security and would be up there at night with others to protect the pocket of second-story apartments and lower-level storefronts near the Ferguson Police Department. A day earlier, rioters had broken out windows below Hildebrand’s apartment in the 100 block of South Florissant Road and torched a nearby beauty supply store.
“I am in the middle of a difficult spot,” Hildebrand said. “I feel a lot better having those guys up on the roof.”

“When they’re here, there’s definitely a weight lifted off of our shoulders,” Davis Vo, whose family owns a local restaurant, told the New York Times, when discussing the Oath Keepers in November. “I’d be lying if I said otherwise.”

What do authorities in Missouri say?

“Their presence was both unnecessary and inflammatory,” St. Louis County Police Chief Jon Belmar said.

In an email to The Post, Brian Schellman, a spokesman for the St. Louis County Police Department, said the agency would “consult” with the St. Louis County Prosecuting Attorney’s Office “about the legalities of the issue.”

A email to a St. Louis County Prosecuting Attorney’s Office spokesman was not immediately returned.

What do the Oath Keepers say?

An e-mail to Oath Keepers was not immediately returned Tuesday.

But here, from the Alex Jones Channel on YouTube, are videos of Oath Keepers engaging with some of the Ferguson protesters:

[This post has been updated.]