They’re already training for this. Doing searches for weapons dealers, drug trafficers and so forth.
They’ll come with overwhelming force.
How long would that take, how many casualties would they suffer, and what would they gain? Are they going door-to-door gun grabbing with overwhelming force? At that point, the decent American’s life depends on those guns, so he might as well take some jackboots with him. Are they taking stored food? Again, same answer.
People with grown children out of the home will not give in quietly, so the thugs can either wear those Americans out with a siege, or look like the brutal modern version of the Gestapo that they are. It would not be one or two Waco/RubyRidge events a decade, it would be many per day if they wanted to get anywhere. I don’t see that happening. They would have to climb out of their tanks to go home pretty much daily, and there would be a whole lot of unhappy people who knew they were on the list for later who would respond unpleasantly.
“They’ll come with overwhelming force.”
Leaving their families unprotected. No plan survives contact with the enemy - and if the enemy (the people) have nothing left to lose and only a few brains, then many will not be at home when that force arrives, they’ll be hunting two-legged creatures that are near and dear to those forces.