FTA: And several laws create exceptions to the Posse Comitatus Act’s general rule. The most important of these is the Insurrection Act. It allows the president, at the request of a state’s governor or legislature, to use federal troops to suppress an insurrection in that state. The president may also deploy troops without a state’s request if an “unlawful obstruction,” domestic violence or similar civil unrest is creating barriers to execution of the law. Troops may be used either to assist local law enforcement or, if necessary, to supplant them. In the latter case, the act authorizes a form of martial law, triggered by vague criteria and with few clear constraints on its use.
'The president may also deploy troops without a state’s request if an “unlawful obstruction,” domestic violence or similar civil unrest is creating barriers to execution of the law.'
Here is the piece that matters.
Thank you - placemarking to read.
We're in festival, but quick reply.
After Hurricane Katrina, a change was made to the Emergency Powers Act, allowing the use of military inside the USA during a National Emergency.
Another article was posted discussing about 137 Emergency Powers available to the President during a National Emergency. He doesn't have to invoke them, but they are available.