There are exceptions to that rule... while they can't arrest people or seize property or conduct searches like a police officer can, they can help maintain order.
George HW Bush did so in 1992.
George W Bush also did so in the aftermath of 9/11.
It involves specific provisions pertaining to Title 10 (responses to terroristic activities), or invoking the Insurrection Act.
I'm actually interested if the administration will invoke the latter... By the progressives' own recent definition of what constitutes a "terrorist attack" and "insurrection", they may have boxed themselves into a corner in terms of being able to argue against the president invoking the Insurrection Act for a situation like this.
If assaulting a government building (in the name of preventing a legal process), while flying the flag of another nation, while making threats against elected officials fits the definition, then it would have to apply to this situation here.
In this instance, people are busting out windows of government buildings while flying Mexican Flags, attacking federal officers, and spray painting (and yelling) the message "
Remove Trump's head!"
Replace the Mexican flags with confederate flags, replace ICE with capitol police, and replace "Remove Trump's Head" with "Hang Mike Pence", and the two sets of circumstances are starting to have some similarities.
