I read the timeline for 1/6/20 and the Head or Chief of the Capitol police had asked for the National Guard before and during the protest. His requests were denied during because the general said it would be something along the lines of bad "optics" to have the Guard confronting protesters in front of the Capitol. Before 1/6/20 the reason given, according to the former of Head/Chief of police, was the general didn't want the presence Guard to be viewed as a provocation or as an acknowledgment that the gov't expected the protests to turn violent.