Your right this is speculative. But its informed speculation. To believe the opposite of whats presented here (the overall picture not the nitty gritty details which are impossible to know) means that Trump was negligent in his duty under the Constitution. He would not now be doing what he is doing if he had been negligent.

So I dont know how big it is or what they call themselves (Army of Northern Virginia?) but I guarantee that there is a large force of military and ex military acting as a unified command.