Donald Trump, yesterday:
Mayors and governors must establish an overwhelming law enforcement presence until the violence has been quelled.
If a city or a state refuses to take the actions that are necessary to defend the life and property of their residents, then I will deploy the United States military and quickly solve the problem for them.
Um, that's against the law:
Whoever, except in cases and under circumstances expressly authorized by the Constitution or Act of Congress, willfully uses any part of the Army or Air Force as a posse comitatus or otherwise to execute the laws shall be fined under this title or imprisoned not more than two years, or both.
Indeed the Congress reaffirmed the law's importance in 2012:
Section 1385 of title 18 (commonly known as the “Posse Comitatus Act”) prohibits the use of the Armed Forces as a posse comitatus to execute the laws except in cases and under circumstances expressly authorized by the Constitution or Act of Congress.
The Congress further defined:
Existing laws, including chapter 13 of title 10 (commonly known as the “Insurrection Act”), and the Robert T. Stafford Disaster Relief and Emergency Assistance Act (42 U.S.C. 5121 et seq.), grant the President broad powers that may be invoked in the event of domestic emergencies, including an attack against the Nation using weapons of mass destruction, and these laws specifically authorize the President to use the Armed Forces to help restore public order.However, the first statement of the Insurrection Act goes like this:
Whenever there is an insurrection in any State against its government, the President may, upon the request of its legislature or of its governor if the legislature cannot be convened, call into Federal service such of the militia of the other States, in the number requested by that State, and use such of the armed forces, as he considers necessary to suppress the insurrection. [Emphasis added.]
The Stafford Disaster Relief bill deals with federal responses after a natural disaster.
Would-be Dictator Trump simply does not have the authority to deploy the military into a state whenever he decides that that state's governor has "refused to take the actions" he deems "necessary."
But when has that ever stopped him? When has that ever stopped his enablers in Congress? By the way, where the fuck are all the conservative "States' Rights!" fetishists, these days? Where are all those members of Congress forever hair-triggered to scream "Executive Overreach!" whenever a president from the Democratic Party did something they didn't like?