The Post said that last Tuesday, an FBI office in Norfolk, Virginia, issued an "explicit internal warning that extremists were preparing to travel to Washington to commit violence and 'war.'" The report "painted a dire portrait of dangerous plans, including individuals sharing a map of the complex's tunnels, and possible rally points for would-be conspirators to meet up" in several states before heading to Washington.
The Post report presents a more vivid picture of some of the threatening and violent discussions that alarmed law enforcement but did not lead to increased security. Law enforcement officials have indicated to CNN that authorities missed key signs ahead of the siege, which left five dead and the Capitol ransacked.
The Post report is also likely to raise additional questions about why authorities were unprepared to respond to the riot and federal readiness to thwart future threats at a time when the FBI is warning of armed protests ahead of President-elect Joe Biden's inauguration.
The report referenced an online thread in which conspirators discussed their plans, quoting individuals as saying: "'Be ready to fight. Congress needs to hear glass breaking, doors being kicked in, and blood from their BLM and Pantifa slave soldiers being spilled. Get violent. Stop calling this a march, or rally, or a protest. Go there ready for war. We get our President or we die. NOTHING else will achieve this goal.'"
The information was "briefed to FBI officials at the bureau's Washington field office the day before the attack," the Post reported. The newspaper, however, said the document is clear that the information presented was not "finally evaluated intelligence," and that agencies receiving it "are requested not to take action based on this raw reporting without prior coordination with the FBI."
The newspaper also reported that the FBI was careful with its description of the individuals and organizations listed in the report, with the bureau writing that the activities they engaged in are protected by the First Amendment to the Constitution and that though they were mentioned in the report, "Their inclusion here is not intended to associate the protected activity with criminality or a threat to national security, or to infer that such protected activity itself violates federal law."
But the report also warned that "based on known intelligence and/or specific historical observations, it is possible the protected activity could invite a violent reaction towards the subject individual or others in retaliation or with the goal of stopping the protected activity from occurring in the first instance," according to the Post.
Key warnings ahead of attack
Officials told CNN last week that going into Wednesday, they had no intelligence indicating there was a threat the US Capitol could be overrun. In the wake of the attack, federal and local officials have said they did not have intelligence suggesting any violent mob was preparing to attack the Capitol, even as demonstrators were publicly saying on social media they were not planning a typical protest.
The Post's report prompted Rep. Ted Lieu, a California Democrat who is a member of the House Judiciary Committee, to call for his panel to open a probe about the matter.
Former Virginia Republican Rep. Denver Riggleman, who is working with several former national security officials to analyze open source information about the attack, also called for an investigation.
"There is a clear breakdown of communications and operational chain of command. It would be interesting to see what the internal intelligence memos were for Capitol Police and support elements. My guess is that the intelligence reports would have had a possible Capitol incursion," he told CNN.
There were reports of violence when President Donald Trump's backers had come to town last month, and the FBI was monitoring everything from social media to the hotels where some of the rioters were staying. One sign of the preparations came in the days before a rally held by Trump last week just before the attack, when, acting on the FBI's intelligence information, Washington's Metropolitan Police arrested Enrique Tarrio, leader of the Proud Boys, after he left the airport en route to his hotel.
He was charged for his role in destroying a Black Lives Matter banner at a previous Proud Boys march in Washington, and prosecutors later added charges of carrying two extended ammunition magazines that are illegal in the city. As part of his release, a local judge told him to leave town and to stay away from last Wednesday's rally.
Nation on edge ahead of inauguration
Complicating last week's response was a division of responsibilities for security -- Capitol Police reports to Congress and is separate from the executive branch agencies, including the FBI and Secret Service, which don't have jurisdiction on the Capitol grounds unless requested by the Capitol Police.
The Post report comes amid a heightened sense of alarm nationwide leading up to Biden's inauguration and efforts by authorities to prevent another catastrophe.
An internal FBI bulletin obtained by CNN shows the bureau has received information indicating "armed protests" are being planned at all 50 state capitols and the US Capitol in the coming days, and lawmakers have been briefed on threats to the US Capitol ahead of the inauguration.
Federal officials, however, have yet to hold a news conference since Wednesday's incursion, prompting objections from lawmakers who say media briefings after such incidents are common. And on Monday, acting Homeland Security Secretary Chad Wolf resigned, citing ongoing litigation challenging the validity of his appointment, raising further questions about the leadership of a key department involved in national security ahead of the inauguration.
This story has been updated with additional background information and reaction.
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