Alek Minassian, the man who killed 10 people by driving a van down a busy street in Toronto on Monday, is a terrorist.

We know this because he told us so. On Tuesday afternoon, Facebook confirmed the authenticity of a post in his name, in which he pledged allegiance to something called the “Incel Rebellion.” This is not an organized militant group but rather an ideal developed by the so-called “incel” movement — an online community of men united by their inability to convince women to have sex with them. (“Incel” stands for “involuntarily celibate.”)

Some self-identified incels, as they call themselves, have developed an elaborate sociopolitical explanation for their sexual failures, one that centers on the idea that women are shallow, vicious, and only attracted to hyper-muscular men. They see this as a profound injustice against men like them, who suffer an inherent genetic disadvantage through no fault of their own. A small radical fringe believes that violence, especially against women, is an appropriate response — that an “Incel Rebellion” or “Beta [Male] Uprising” will eventually overturn the sexual status quo.

Minassian is not the first to turn these violent fantasies into reality. In 2014, a sexually frustrated man named Elliot Rodger killed six and wounded 14 in a shooting spree in Santa Barbara, California. He justified his actions in a lengthy and creepy manifesto sent to acquaintances and then widely shared online as retaliation against women as a group for refusing to provide him with the sex he is owed. This man has become a hero to many incels; the Toronto perpetrator praised him as the “Supreme Gentleman” (a term the California shooter coined for himself) in his Facebook post.

Only a tiny percentage of incels seem willing to turn to violence or terrorism, and the movement isn’t a threat on the level of an al-Qaeda or ISIS. But it’s a new kind of danger, a testament to the power of online communities to radicalize frustrated young men based on their most personal and painful grievances.

The Facebook post “situates the attack as extremist and terrorist,” says J.M. Berger, an expert at the International Center for Counter-Terrorism in the Hague. “Misogyny isn’t new, and ideological misogyny isn’t new. Having a distinct movement that is primarily defined by misogyny is [fairly] novel.”

Incel, explained

When we talk about “incels,” we are not talking about all men who are not having sex. Instead, we are talking about a specific subculture of people in various internet forums — subreddits like r/braincels, the cruel troll chat forum 4chan, and dedicated websites like incels.me.

Beyond their shared frustration with not having sex, the incel community is not monolithic. Many of them are simply sad and lonely men, suffering from extreme social anxiety or deep depression. Some of these moderate incels actively police the extremists in their midst; in a sympathetic 2015 profile, the Washington Post’s Caitlin Dewey reported that some incel forums were set up to automatically delete any posts referencing the California shooter.

But many incels have a much more sinister, and specific, worldview — one that the Southern Poverty Law Center sees as part of a dangerous trend toward male radicalization online. These incels post obsessively about so-called “Chads,” meaning sexually successful and attractive men, and “Stacys,” attractive, promiscuous women who sleep with the Chads. Both are positioned as unattainable: The Chad is the masculine ideal, one incel men cannot emulate for reasons of poor genetics, while the Stacy is whom every incel man wants to sleep with but cannot because they aren’t a Chad.

It’s this embrace of helplessness, of their certainty of their own sexual doom, that makes the more extreme incel communities so dangerous. Instead of trying to support each other and work through their issues as a group, the incels in certain communities allow their resentments to curdle. They see the world through the lens of entitlement: They are owed sex but cannot have it because women are shallow. This manifests in a deep and profound hatred for women as a group, which shows up on a very brief scan of some of the more extreme incel communities.

“I have sluts for managers,” one poster on the incel.me forum wrote. “Flat bitch with no ass and loud ugly black landwhale somehow with no ass either ... both brag about all the dick they suck.”

But it’s not just individual women that these radical incels hate — it’s society writ large, a society that allows their perceived sexual oppression to go on. The sexual revolution, in particular, comes in for hate: They believe women being freed to make their own sexual choices, rather than being married off to men and made subordinate, is the reason women can choose to sleep with attractive men and ignore the so-called incels.

This is how inceldom becomes a political doctrine: They see themselves as a class, oppressed by a social system that’s rigged in favor of other men. One post on an incel subreddit compared their worldview to Marxism, with incels playing the part of the proletariat and Chad the bourgeoisie. The natural corollary of this idea is clear: If the root of the problem is an unfair social system, then there needs to be a revolution to change it.

This is where the idea of the “Incel Rebellion” that Minassian referenced comes from — sometimes called “Beta Uprising” on incel forums, a reference to beta males. There’s no centralized planning, no incel equivalent to of Osama bin Laden. There are just men on various online forums celebrating violence and forming a mutually supportive echo chamber that justifies harming others, especially women, in the name of the incel uprising.

“I do not blame Alek Minassian for what he did,” another poster on incels.me writes. “I blame society for treating low status men like garbage. There will always be more rampages because of the way society treats us.”

Some of the reactions to the Toronto attack have been even more extreme. David Futrelle, a journalist who follows the incel movement on his site We Hunted the Mammoth, took screenshots of some of the most extreme pro-Minassian posts, in which posters call for more “ERs” (attacks like the California shooter’s). Here’s one of the worst ones (highlights by Futrelle):

This is the stuff of terrorist incitement and recruitment. The appeal to male frustration in these communities serves, as my colleague Aja Romano has written, as a kind of gateway. Men log on to complain about their loneliness and dating failures and end up getting sucked into a community that encourages them to blame women and society for their problems. And eventually, some of them decide to do something about it.

This is a terrorist movement. What can be done about it?

Terrorism is a notoriously difficult concept to define, but the most widely accepted definition among scholars is that terrorism is a form of violence directed against civilians by a non-state actor with the goal of achieving some kind of political end. By that standard, there is no doubt that the Toronto attack fits the bill. The perpetrator wasn’t taking revenge on a specific woman who wronged him; he wanted to instill terror in society writ large as a means of furthering the incel rebellion against the sexual status quo.

“Morally, it is important to recognize such acts as terrorism,” Stephanie Carvin, a professor at Carleton University in Ottawa, tells me.

This is not a familiar type of terrorism. The groups we hear about the most tend to have more understandable political goals, like installing an Islamist regime or winning the right for their region to secede from a country. The incel rebellion has a much more amorphous endpoint; there’s no worked-out vision for what success looks like, nor is there a chief ideologue working to come up with one. You just have a bunch of random internet forum posters pushing one another toward violence.

While extremist groups are quite commonly misogynistic and even recruit based on male sexual frustration, their ideologies almost never center on that fact. There have been mass acts of misogynistic violence before, as in the 1989 shooting at Montreal’s École Polytechnique that claimed the lives of 14 women, but there wasn’t a large online community providing an ideology that justified the killer’s grievances. The incel turn toward violence is a unique phenomenon, at least in the modern era.

This creates a fairly difficult challenge for law enforcement agencies. On the one hand, there is a real terrorist threat from incel communities; it’s clearly not all talk. On the other hand, there are serious risks that come along with having American and Canadian law enforcement officials trawling Reddit for people to arrest.

“I’m not sure national security agencies are best placed to handle places like 4chan,” Carvin says. “We want to keep the law narrow enough that we aren’t monitoring all different kinds of dissent.”

There’s also a serious identification challenge. Online communities are both full of empty talk and draped in irony, making it tough for social media companies and law enforcement officials to figure out who is a threat and who isn’t.

“[The perpetrator’s] post really highlights the challenges facing the social media companies. It read like a joke or nonsense,” Berger, the terrorism expert, tells me. “How are you supposed to evaluate something like that?”

Does this mean we should just throw up our hands and say that the radicalization of some young men toward violent misogyny is inevitable? Of course not. Carvin suggests that social outreach programs, focusing on countering the sense of isolation that draws young men to these communities in the first place, might be a better idea than standing up a potential counter-incel task force at the FBI. (No such group is currently known to exist.)

But regardless of what the right solution is, we need to be clear-eyed about the type of challenge we’re facing. The internet makes it easier than ever for sad and angry people to find each other and develop communities with weird and dangerous ideologies. What we’re seeing right now is one of society’s oldest hatreds, misogyny, being reworked in real time to fit a specific group of men’s rage and pain.

And 10 people in Toronto just died as a result.