They don't need to overthrow democracy, they just need to use jurisdiction removal to have the state charges placed in federal court, and then appeal it up to SCOTUS who will overturn the decision.

The US couldn't win a war in the middle east with trillions of dollars, thousands of soldiers dead, and tens of thousands substantially wounded. Hasn't won a war since WW2. Is everything going swimmingly? Certainly not. There are 340M Americans, ~20k-30k ICE folks, and ~1M soldiers on US soil. These odds don't keep me up at night. 77% of US 18-24 cohort don't qualify for military service without some form of waiver (due to obesity, drug use, or mental health issues).

I admit, US propaganda is very good at projecting an image of strength. I strongly doubt it is prepared for a civil ground war, based on all available evidence. It cannot even keep other nation states out of critical systems. See fragile systems for what they are.