Major General William Walker who acts as the commanding general of the District of Columbia National Guard told senators in Washington DC on Wednesday that it took more than three hours for the Defense Department to approve a request from the National Guard to intervene on the day of the attack on the US Capitol, delaying help despite an urgent plea from police for reinforcement.

"It shouldn't take three hours to either say "yes" or "no" to an urgent request from either the Capitol Police, the Park Police, the metropolitan police department. In an event like that where everybody saw it, it should not take three hours," said Walker who added then-Capitol Police Chief Steven Sund pleaded with him by phone to send in troops shortly in a "cracking" voice.

A joint Senate committee has launched an investigation into the apparent US government failure to respond adequately to the Capitol storming incited by the former US President Donald Trump which left five people dead in its wake.