In wake of Capitol riot, feds warn that violent extremists likely pose 'greatest domestic terrorism threats'

Violent extremist activity will likely surge in the United States and pose "the greatest domestic terrorism threat in 2021," a trio of federal law enforcement agencies warned in a recently released bulletin.

The FBI, the Department of Homeland Security and the National Counterterrorism Center announced in a Joint Intelligence Bulletin released Wednesday that this threat comes from "anti-government or anti-authority violent extremists," such as militia violent extremists (MVEs), racially or ethnically motivated violent extremists and domestic violent extremists "citing partisan political grievances." The document was first obtained and published by Yahoo News.

"In 2021, threats and plotting of illegal activity, including destruction of property and violence targeting officials at all levels of the government, law enforcement, journalists and infrastructure, as well as sporadic violence surrounding lawful protests, rallies, demonstrations, and other gatherings by [domestic violent extremists] will very likely increase due to renewed measures to mitigate the spread of COVI-19, socio-political conditions, and perceived government overreach," the bulletin states.

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The memo was released in the wake of last week’s attack on Capitol Hill. On Jan. 6., hundreds of apparent Trump supporters stormed the U.S. Capitol building – some armed with guns or zip-ties – where they smashed or dismantled property and went into House and Senate leaders’ chambers. Meanwhile, Hill staffers and lawmakers were under lockdown, or hid behind chairs or under desks and tables.

Five people, including a U.S. Capitol Police officer, died during or in connection with Wednesday's events. 

The bulletin further describes how the events of Jan. 6 "will very likely serve as an enduring driver for violence by a range of domestic violent extremists."

The siege and the subsequent deaths of those involved "very likely will serve to galvanize [domestic violent extremists] and increase collaboration" between the other extremists, the document states. The extremists "may also perceive the event as a step toward achieving their initiatives, and consider the death of a perceived like-minded individual as an act of martyrdom."

On Monday, a federal law enforcement source told Fox News an internal bureau memo was circulating that warned of armed protests that would be held in all 50 state capital cities in the days leading up to Inauguration Day on Jan. 20.

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Yahoo News later exclusively reported that the FBI’s Minneapolis Field Office memo – sent to local and state agencies at the end of December – cited "collaborative sources" who told investigators that members of the "boogaloo" movement would be hosting potentially violent events on Jan. 17.

Speaking to the potential for increased violence in 2021, the bulletin describes how this year – when domestic violent extremists "perceive increased socio-political pressures following the Presidential Inauguration" – they "may be inspired to carry out more violence, including violence against racial, ethnic, and religious minorities and associated institutions, journalists, members of the LGBTQ+ community, and other targets."

The document cites events that could potentially turn violent and identifies motivating factors as being "false narratives" about the 2020 General Election’s legitimacy, COVID-19 requirements and measures and conspiracy theories.

In the coming days, domestic violent extremists "could exploit upcoming events to engage in or justify violence, including events attended by MVEs and 'boogaloo' adherents scheduled nationally from 16 to 20 January; the 20 January Presidential Inauguration and associated events ... and any departure of the 45th President from office prior to the end of his term," the agencies warned. 

Meanwhile, after last week’s insurrection, investigators are combing through a mountain of online posts, street surveillance and other intelligence, including information that suggests mobs could try to storm the Capitol again and threats to kill some members of Congress.

Thousands of National Guard troops are protecting the Capitol ahead of President-elect Joe Biden’s inauguration. Governors and lawmakers are also stepping up protections at statehouses after an FBI bulletin this week warned of threats to legislative sessions and other inaugural ceremonies.

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A primary concern is the safety of members of Congress, particularly when they are traveling through airports, two U.S. officials briefed on the matter told the Associated Press.

Since last week, the FBI has opened 170 case files and has received more than 100,000 pieces of digital media. The threats have ranged in specificity and complexity, according to officials briefed on them, making it difficult for authorities to determine which could be credible.

Fox News' David Spunt and the Associated Press contributed to this report.