You dont need your military to secure your southern border. Just the border guards you already have, and a rational policy. Trump did secure your border, simply by giving the proper orders. If you want that to happen again, you need to remove your current president and replace him with a better one, amenable to your wishes.
And without that president you cant move your army anyway, not that its necessary to do so.
So its entirely up to you. No military fantasies are needed, its just a matter of political power. Go get it.