Stochastic terrorism appears to be on the rise globally. Extremism experts explain how this form of violence has gone mainstream.

• Acts of stochastic terrorism appear to be on the rise, according to extremism experts.
• Stochastic terrorism is a type of extremist violence that is borne of increasing polarization.

The violent attack against House Speaker Nancy Pelosi's husband last month marked a noted escalation of brewing political violence in the US, with the suspect telling authorities that he broke into the lawmaker's home with zip ties as a warning to other Democrats.

Authorities believe the alleged assailant worked alone to execute his plan — but he offered familiar rhetoric as the reason for the attack, according to police, parroting conspiracy theories and lies that have been embraced by the far-right.

The "lone-wolf" nature of the assault in conjunction with the suspect's stated motivation suggests the incident could be an example of stochastic terrorism, according to extremism experts.

Stochastic terrorism is a specific type of extremist violence that occurs when an environment has "othered" a population or individual to a significant enough extent that results in subsequent violence against them, Eric K. Ward, senior advisor to the Western States Center, told Insider.

Ward cited the uptick in hate crimes against Middle Eastern Americans immediately following the September 11 attacks as a prime example of stochastic terrorism in practice. The 2011 shooting of former Congresswoman Gabby Giffords is another instance of the phenomenon, according to Ramon Spaaij, a sociology professor who specializes in the study of violent extremism and terrorism.

No legitimate organization or public figure explicitly enabled the 22-year-old shooter to attack Giffords, nor did any politician directly encourage people to enact violence against Middle Easterners following 9/11, Spaaij explained, but an environment of extremism and polarization paved the way for their actions.

"These are individual attacks, but actually there are patterns in the sense that if you create a polarized-enough environment with hate speech and conspiracy theories that pits particular groups against each other, that really starts undermining the legitimacy of democratic institutions and people's trust," Spaaij told Insider.

The ongoing delegitimization of such institutions — as well as the people who operate within those institutions — creates an environment that then lowers the threshold for and legitimizes violence as a result, according to Spaaij, who wrote about stochastic terrorism in his 2017 book "The Age of Lone Wolf Terrorism."

Extremism experts say political violence has gone mainstream

Stochastic terrorism is a term that primarily pops up in modern conversations of extremism, particularly in the context of "lone wolf violence," experts said. But the concept has its roots in the anarchism of the late 19th century, in which much of the resistance, propaganda, and extremism of the time was leaderless and decentralized, according to Spaaij.

While stochastic terrorism is not a new phenomenon, its stark prevalence in global society at the moment is a more recent development, he added.

"It's quite mainstream," Spaaij said, of stochastic terrorism. Access to inciting ideas is no longer available only in obscure, radical pamphlets and materials. "It's actually right out there and it really infiltrates mainstream political discourse," he added.

There's no one factor fully responsible for stoking stochastic terrorism. It can happen through a combination of mainstream media, polarizing political discourse, and more and more frequently via social media, Spaaij said.

"We're seeing that now play out on Twitter for example," he said. "Where's the line between misinformation and hate speech?"

"Particular platforms reinforce and reify these beliefs and that's all [people] hear," he added. "So it's a funneling. There is no room anymore for different perspectives that might challenge that."

Rep. Alexandria Ocasio-Cortez invoked the term in a Tuesday interview ahead of the midterm elections, saying she routinely receives a wave of death threats anytime she is mentioned by Tucker Carlson on Fox News.

"This is what stochastic terrorism is," she said. "When you use a very large platform to turn up the temperature and target an individual until something happens."

Sub-groups prone to stochastic terrorism have a strong sense of moral righteousness and have often created a strict binary between good and evil for themselves, casting their enemies as villains, Spaaij said.

"It's a lot easier to harm someone when they've been dehumanized," he added.

The suspect in the Pelosi attack last month told authorities that he saw the lawmaker as the "leader of the pack" among Democrats and planned to break her kneecaps if she "lied" so she would have to be wheeled into Congress as a message to other lawmakers that "there were consequences to actions."

It's a chilling example of how the baseless conspiracy theories about the top woman in Congress have not only wormed their way into the mainstream GOP, but have become so prevalent and pernicious to inspire individuals to act on them.

Stochastic terrorism appears to be on the rise globally

The unpredictability and decentralized nature of stochastic terrorism make combatting the violence particularly difficult, especially when it comes to accountability.

The individual perpetrator of a violent attack can obviously be held to account. But trying to point the finger at the politician or public figure that fueled the flames that ultimately inspired said individual to act is much more challenging.

"It's very easy to deny any accountability around that," Spaaij said. "It's more indirect, not causal."

But without any accountability, a vicious cycle materializes and these environments of hate are able to flourish, ensuring further displays of violence, experts said. Acts of stochastic terrorism appear to be on the rise around the world, according to Spaaij and Ward, who cited anti-immigration waves in several European countries and increasing attacks and threats against US politicians as evidence.

The legitimization of dangerous rhetoric makes consequences certain.

"We know that an attack will inevitably take place at some point in time," Spaaij said. But what makes the violence stochastic, he added, is "we don't know where or when."