Dozens of people on the FBI's terrorists watchlist were in DC during the siege on the Capitol showing yet another security failure

• Dozens of people on the FBI's terrorist watchlist were in Washington, DC, during the siege on the Capitol last week, The Washington Post reported.
• The FBI warned some on the list not to go, but dozens still went.
• It's not clear if any of those already arrested for charges relating to the ransacking of the Capitol were on the FBI list.

Dozens on the Federal Bureau of Investigation's terrorist watchlist - mainly those categorized as white supremacists - were in Washington, DC, on the day the Capitol was stormed, The Washington Post reported.

The new information comes after it was found that a January 5 FBI report had warned that pro-Trump insurrectionists were planning to wage a "war" at the US Capitol the next day.

On January 6, supporters of President Donald Trump breached the Capitol and clashed with law enforcement, halting the joint session of Congress as lawmakers were debating challenges to electoral votes. Five people died, including a Capitol Police officer and a woman who was shot by law-enforcement officials.

One week later, Trump became the only president in US history to be impeached twice after the House of Representatives brought forth an article of impeachment against him on a charge of "incitement of insurrection."

FBI agents had visited some suspected extremists on the list and advised them not to travel to the Capitol ahead of the certification, but dozens still did so, The Post reported.

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However, it's not clear if any of the people already arrested on charges relating to the siege are on the FBI's list.

"The US Government is committed to protecting the United States from terrorist threats and attacks and seeks to do this in a manner that protects the freedoms, privacy and civil rights and liberties of US persons and other individuals with rights under US law," A US government official told Insider. "Because of security concerns, the USG's general policy is neither to confirm nor deny a person's watchlist status."

The Post's report highlights yet another security failure as dozens of people from the watch list gathered in one location. The Post reported that the watch list is different than the "no-fly" list and putting someone's name on it does not necessarily mean they're going to constantly monitored or barred from traveling. However, the list allows border agents or state police to look more closely at individuals they encounter if their name is on it.

The Post added that several law enforcement officials told them they were shocked at the backgrounds of some of the people under investigation for the riot.

"I can't believe some of the people I'm seeing," one official said.

A US Navy veteran, a retired US Air Force Lt. Col, and an infantryman in the Virginia National Guard were some of the people arrested for breaching the Capitol.