> BUT there is no sign that Active Duty military personnel are being deployed to engage civilians (yet).
Yes, there is.
> It would seem most likely that the Marines were called strictly to protect federal buildings, facilities and agents.
So, to engage civilians deemed a threat to federal buildings, facilities, and agents.
The distinction you are trying to draw does not exist, and is simply a very weak attempt to craft a mission that can be argued not to be using the military as a posse comitatus (even though it clearly is exactly that) for the sole purpose of reserving invoking the Insurrection Act until the aggressive use of federal forces has been successful in provoking a suitably dramatic incident.
Yes, there is.
> It would seem most likely that the Marines were called strictly to protect federal buildings, facilities and agents.
So, to engage civilians deemed a threat to federal buildings, facilities, and agents.
The distinction you are trying to draw does not exist, and is simply a very weak attempt to craft a mission that can be argued not to be using the military as a posse comitatus (even though it clearly is exactly that) for the sole purpose of reserving invoking the Insurrection Act until the aggressive use of federal forces has been successful in provoking a suitably dramatic incident.