Michigan, Virginia, Wisconsin, Pennsylvania and Washington are among the states that have activated their National Guards to strengthen security.
Prosecutors behind the filing asked a judge to detain Jacob Chansley, the Arizona man and QAnon conspiracy theorist who was famously photographed wearing horns inside the Capitol.
The agency also said it has identified over 200 suspects.
The FBI warned law enforcement agencies ahead of last week's breach of the U.S. Capitol about the potential for extremist-driven violence, U.S. officials said on Tuesday.
Across Washington, officials are preparing for Inauguration Day amid rising safety concerns.
The statement was accompanied by an image of a masked suspect wearing gloves and a hooded sweatshirt, carrying an object.
Several people photographed at the pro-Trump riot have been fired, and the FBI is looking to identify many others for possible criminal charges.
The FBI is offering a reward of up to $50,000 USD for information on who placed pipe bombs in the committee headquarters of U.S. political parties in Washington.
Evidence is still being reviewed, but investigators are known to be reviewing whether Anthony Warner believed in conspiracy theories involving aliens and 5G cellphone technology.
The rare joint statement represented the U.S. government's first formal attempt to assign responsibility for the breaches at multiple agencies and to assign a possible motive.
In tweets Saturday morning, Trump said the cyberattack is 'far greater in the Fake News Media than in actuality.'
Officials widely suspect Russia is behind the attack, although the joint statement from the FBI and other U.S. agencies does not say who investigators believe is responsible.
A senior manager with the Canada Border Services Agency said she put requests up the CBSA chain to see if headquarters would approve the FBI request or appoint a contact person.
The FBI's annual report defines hate crimes as those motivated by bias based on a person's race, religion or sexual orientation, among other categories.
A man charged in an alleged conspiracy to kidnap Michigan's governor also made threatening online comments about U.S. President Donald Trump, former presidents Barack Obama and Bill Clinton and other prominent political figures, an FBI agent said ...
The announcement of the firing came shortly after the FBI joined Illinois State Police in investigating the shooting late Tuesday of Marcellis Stinnette, 19, and the wounding of his girlfriend, Tafara Williams.
U.S. officials said said Russia has obtained some voter information as well, but has not yet conducted any actions similar to Iran's.
The suspects allegedly belonged to a far-right militia group that discussed overthrowing state governments.