'I was frustrated': D.C. National Guard chief on Capitol riot response

"At 1:49 p.m. I received a frantic call from then-Chief of U.S. Capitol Police, Steven Sund, where he informed me that the security perimeter at the Capitol had been breached by hostile rioters," said Maj. Gen. Walker. "The approval for 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 p.m., about three hours and 19 minutes later."

Then-acting Defense Secretary Christopher Miller was installed by former President Donald Trump days after Democrat Joe Biden was declared the winner of the November election.

Walker and other U.S. officials testified before a joint hearing conducted by the U.S. Senate Homeland Security and Senate Rules committees titled "Examining the January 6 Attack on the U.S. Capitol, Part II."