"The Committees will conduct robust oversight to understand what warning signs may have been missed, determine whether there were systemic failures, and consider how to best address countering domestic violent extremism, including remedying any gaps in legislation or policy," they continued.

The committees are seeking a series of classified briefings beginning in late January to help lawmakers understand the evidence of threats they had collected, both about Jan. 6 and other threats to the transition of power leading up to Biden's Jan. 20 inauguration.

They're also asking specific questions, including on the evidence each intelligence agency gathered ahead of Jan. 6 and what they did with it; if there was evidence of any foreign efforts to either assist the insurrection, spread misinformation about it or exploit the aftermath; if any current or former officials with security clearances participated in the insurrection; and what policy responses the intelligence agencies have implemented to apprehend rioters and disrupt potential future actions.

For several hours on Jan. 6, the Capitol convulsed in chaos as violent rioters stormed past police lines and sent lawmakers and aides fleeing for safety inside the building. Vice President Mike Pence, a target of some of the insurrectionists, was escorted from the Senate chamber shortly before rioters swarmed it. On Wednesday, the House impeached President Donald Trump for inciting the riot, and federal prosecutors have been rounding up participants in a nationwide manhunt while piecing together evidence.

Democrats have alleged that some of their own GOP colleagues may have had a hand in assisting the insurrectionists, with some saying they witnessed suspicious tours in the Capitol on Jan. 5. Some of the rioters appeared to have significant knowledge of the Capitol complex, which has fueled those concerns.