“The military cannot operate in America due to Posse Comitatus,”
You’re wrong. The military can operate within the U.S. as long as it’s not in a domestic law enforcement capacity.
The 82nd and 101st Airborne Divisions are usually excluded from the act under the Enforcement Act as well as 18 U.S.C. § 831. That’s why you usually see them used for riot control (Detroit, LA), as well as disaster recovery (Hurricanes Andrew and Katrina).
The President can also use the Insurrection Act to restore order.
The US Marshall Service can deputize military members for a Posse as long as they are out of uniform. :D