The Posse Comitatus Act bars federal troops from participating in civilian law enforcement except when expressly authorized by law. This 143-year-old law embodies an American tradition that sees military interference in civilian affairs as a threat to both democracy and personal liberty.
I know this will start an argument, but State National Guards are not considered Federal Troops unless Federalized by the POTUS
Might a President ever be inclined to collaborate with a governor of the same political party on deploying state national guard troops and then federalizing them?