https://media.defense.gov/2021/Jan/11/2002563151/-1/-1/0/PLANNING-AND-EXECUTION-TIMELINE-FOR-THE-NATIONAL-GUARDS-INVOLVEMENT-IN-THE-JANUARY-6-2021-VIOLENT-ATTACK-AT-THE-US-CAPITOL.PDF
Muriel Bowser would have to ask the Defense Department.
Which she did. And acting Defense Secretary Christopher Miller approved the request. https://www.cnn.com/2021/01/04/politics/muriel-bowser-dc-national-guard-protests/index.html
(apologies for it being CNN; if someone wants a different source they can go digging 😉)
So we know the NG is because of a liberal mayor....well, that sucks.
https://media.defense.gov/2021/Jan/11/2002563151/-1/-1/0/PLANNING-AND-EXECUTION-TIMELINE-FOR-THE-NATIONAL-GUARDS-INVOLVEMENT-IN-THE-JANUARY-6-2021-VIOLENT-ATTACK-AT-THE-US-CAPITOL.PDF