Document reveals new details of dramatic Mike Pence call during Capitol attack: "Building not secure"

Friday marks 100 days since the January 6 attack on the Capitol building. New numbers from the Justice Department show more than 400 suspects have been arrested from at least 45 states.

CBS News obtained a copy of the Capitol Police inspector general's findings, which revealed that Capitol Police officers didn't know ahead of time just how serious the threat was on January 6, and they were blocked from using aggressive crowd control tactics.

On January 3, an internal intelligence assessment by the Capitol Police warned January 6 would be different. The reports said, "The targets of pro-Trump supporters are not necessarily the counter-protestors but rather Congress itself." But on the day of the attack, a conflicting assessment said an attack was "Improbable."

An internal Defense Department timeline also obtained by CBS News revealed new details of a dramatic call between then Vice President Pence and then acting Secretary of Defense Chris Miller.

From a safe location inside the Capitol, Pence reported: "Building not secure. What is the timeline? FBI must clear."

Miller recently spoke with CBS News as part of a national security panel discussion, where he said Pence was "focused on clearing the Capitol and making sure that that was done that day so that they could get back to doing the people's business."

"We all brought up the possibility that there was a need for extra security," Kash Patel, Miller's Chief Of Staff, told CBS News' senior investigative correspondent Catherine Herridge.

He was on those January 6 calls and also with Miller three days earlier when they met with former President Trump.

"The president preemptively gave us the authority to deploy the National Guard as the secretary saw fit," Patel said.

The Defense Department memo said Pence pushed Miller and Chairman of the Joint Chiefs of Staff General Mark Milley on why more National Guard troops were "not provided in advance."

On January 4, the memo states Capitol Police confirmed "no requirement" for military support and D.C. Mayor Muriel Bowser wanted a limited Guard presence for traffic control.

But an hour into the riot, at 1:49 pm, an urgent call came in from Capitol Police Chief Steven Sund to the D.C. National Guard pleading for help.

"The approval of Chief Sund's request would eventually come from the Acting Secretary of Defense and be relayed to me by army senior leaders at 5:08 pm about 3 hours and 19 minutes later," Major General William Walker, the commanding general of the D.C. Guard, said during a March 3 hearing.

"Did the Pentagon team slow roll the guard?" Herridge asked Patel.

"No. You can't just send in thousands of uniformed military officers because they say 'Deploy the National Guard.' You have to have a strategic plan with local law enforcement," he responded.

CBS News has also obtained the raw intelligence report from the FBI, which warned of violence the night before the riots that never made it to leadership.

Patel said the Pentagon team had no awareness of the FBI Situational Information Report emphasizing "...it's a law enforcement function to protect the United States Capitol, the FBI and federal agencies."

Outreach to then Acting Secretary Miller, or the Chairman of the Joint Chiefs, from Director Wray or senior FBI leadership on the evening of January 5th might have prompted a dialogue about the threat, but "that that never occurred on January 5th or 6th," Patel said 

This week, senior intelligence and law enforcement officials testified on Capitol Hill that domestic extremism is among the greatest threats facing the country.