said,
"if not (US military).......what then?" US military is required to decide what to do in a case of insurrection. There are indications they're have already taken over some aspects of the country. Example: Harris and likely Xiden not knowing about the military strike in Syria. Another example: General Flynn(brother of Michael) appointed commander of the Pacific theater after Jan 20th is creating a missile system from Japan to the Philippines to counter Xi.
I personally believe Trump split the powers of the president using presidential directory 51. Which is why they tried to impeach him after leaving office.
The US military said they're leaving troops in DC and around the major cities until September.
I have faith the US military will correct this in some way.