The top general of the National Guard has recommended that the president not federalize control of Guard troops so that they can continue to be available to assist state and local governments with law enforcement duties amid the widespread coronavirus outbreak.
Air Force Gen. Joseph Lengyel said that if the federal government assumes control of the Guard, those troops, like active duty U.S. military members, would be forbidden from engaging in domestic law enforcement by the 1878 Posse Comitatus Act.
The dual nature of the National Guard as the primary reserve combat force for the Army and Air Force and the state-level military force is highlighted here. Anything in the Guard mobilized for war leaves little for internal defense under control of the states.
The Reserves are federal-only forces.
In theory, the often elderly, mostly ill-trained, and fairly uniformly ill-funded state defense forces (which includes territories)--where they exist--can fill in when the Guard is in federal service and sent elsewhere.
The key is blurry.
I've mentioned this force before.
Will this crisis lead to more state interest in building up (or in some cases setting up) the capacity of the state defense forces?