The FBI warned in a previously unseen document obtained by Yahoo News that conspiracy theories pose a significant new domestic terrorism threat.

The bureau went on to lay out several events in which individuals' belief in hoaxes and conspiracy theories led to or could have led to violence. They included the Tree of Life synagogue shooting, the Pizzagate conspiracy, and the QAnon conspiracy.

The FBI's assessment is noteworthy given the uptick in not just the number of conspiracy theories saturating the mainstream political sphere, but the ease with which they're spread.

A number of conspiracy theories — and the outlets that publish them — have even found their way into the White House.

President Donald Trump famously pushed the birther conspiracy alleging that Barack Obama was not born in the US; he and his allies claim he's the victim of a "deep state" plot to overthrow him; and he supported the "Spygate" conspiracy theory.

He is also cozy with right-wing and far-right media figures who have embraced conspiracy theories about mass shootings and the murder of the Democratic staffer Seth Rich.

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A previously unseen FBI document obtained by Yahoo News warns that conspiracy theories pose a new domestic terrorism threat.

"The FBI assesses anti-government, identity based, and fringe political conspiracy theories very likely motivate some domestic extremists, wholly or in part, to commit criminal and sometimes violent activity," the document said. "The FBI further assesses in some cases these conspiracy theories very likely encourage the targeting of specific people, places, and organizations, thereby increasing the likelihood of violence against these targets."

The document continued to say that the bureau reached its conclusion "with high confidence" and based on information it obtained from other federal agencies, open source information, court documents, FBI investigations, and human sources.

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The bureau went on to lay out several events over the last several years in which "perpetrators intended to kill groups identified by such theories as hostile and malevolent," or to carry out "dangerous, unlawful acts in an effort to draw attention to or expose a perceived conspiracy." They included:

When a California man was arrested in December after intending to blow up a satanic temple monument in the Illinois capital building to make Americans "aware of 'Pizzagate' and the New World Order (NWO), who were dismantling society." Pizzagate refers to a 2016 conspiracy theory in which then Democratic presidential nominee Hillary Clinton's campaign was accused of running a child sex trafficking ring out of a Washington, DC, pizza parlor.

The October 2018 mass shooting at the Tree of Life synagogue in Pittsburgh, Pennsylvania, which resulted in 11 deaths and several injuries. The alleged shooter, Robert Bowers, had a history of violent and anti-semitic beliefs. Shortly before the attack, Bowers posted on social media that the Hebrew Immigrant Aid Society "likes to bring invaders in that kill our people. I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in."

When a Nevada man used an armored truck to block traffic on the Hoover Dam Bypass Bridge in June 2018. He was arrested after fleeing to Arizona and authorities found body armor, ammo, rifles, and a flash-bang device inside his vehicle. Citing a technical source with direct access, the FBI said the man directly referenced the QAnon conspiracy theory after his arrest. The media also reported that he sent letters to President Donald Trump from jail that featured a QAnon slogan.

When two men were arrested in October 2016 on drug charges and were found to be planning an attack on the High Frequency Active Auroral Research Program (HAARP), a government-funded research facility. The men apparently believed the US government was using HAARP to control the weather and prevent people from talking to God.

When Paul Anthony Ciancia shot and killed a Transportation Security Administration (TSA) officer and wounded several others at Los Angeles International Airport in November 2013. Before the attack, Ciancia wrote a letter expressing his desire to kill TSA personnel, whom he believed were associated with the New World Order conspiracy theory.

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The FBI's assessment is particularly noteworthy given the uptick in not just the number of conspiracy theories but the ease with which they're spread.

"The advent of the Internet and social media has enabled promoters of conspiracy theories to produce and share greater volumes of material via online platforms that larger audiences of consumers can quickly and easily access," the document said.

Indeed, a number of conspiracy theories — and the outlets that publish them — have even found their way into the White House. President Donald Trump famously pushed the baseless claim that President Barack Obama was not born in the United States.

Since he took office, the president and his allies have often suggest that he is the victim of a "deep state" conspiracy to undermine his presidency and ultimately remove him from office.

Many Trump supporters have also embraced the so-called "Spygate" conspiracy theory in recent months, which alleges, without proof, that the FBI planted a spy within the Trump camp during the election to undermine his campaign.

Read more: 'A f---ing travesty': Justice Department veterans say the way Mueller's testimony was handled blew past the 'historical significance of this moment'

Trump is also cozy with Alex Jones, the founder of the far-right conspiracy website InfoWars.

Jones, who has a history of making outlandish claims about the Democratic party and left-wing politicians, drew immense backlash when he suggested that the 2012 Sandy Hook Elementary School shooting was a false-flag operation so the government could seize peoples' guns.

Meanwhile, the right-wing media sphere, including staunch Trump ally Sean Hannity, whipped itself into a frenzy after the 2016 election when a fake news report said the Democratic National Committee was connected to the death of former DNC staffer Seth Rich.

Law enforcement authorities say Rich's murder was in fact tied to a robbery, and a Yahoo News investigation recently revealed that Russian intelligence was originally behind spreading the conspiracy theory.