Two senior Pentagon officials defended on Tuesday their management of the assault on the Capitol on Jan. 6, while a prominent congresswoman called the delay in responding to the attack a "shocking failure" and increased pressure for a thorough investigation.

During a nearly five-hour hearing, the Democratic majority in the US House of Representatives said that the Capitol Police, Washington Metropolitan Police and local officials made at least 12 urgent requests for support from the DC National Guard on Jan. 6, before Defense Secretary Chris Miller authorized it at 4.32 pm.

"That response took far too long," House Oversight Chairwoman Carolyn Maloney said.

"After a series of delays, the National Guard did not arrive until 5.20 pm, more than four hours after the Capitol perimeter was breached. This is a shocking failure."

The data provided by Maloney comes from an investigation by her committee into what happened on Jan. 6, when a mob of extremist supporters of then-president Donald Trump stormed the Capitol with the aim of interrupting a session to ratify the electoral victory of now-president Joe Biden, in an assault that ended in five deaths.