Reforming the police helps, but disbanding it does not. Tribes were denied the ability to police themselves locally, thus as I stated above IS what happens when this happens. It will be even worse for a city like Portland because it will be so televised and widespread, they are essentially putting a beacon on the city for every criminal in the US to come for a free for all. At least on the reservation, they are more secluded and less well known and it is mostly spread by word of mouth, but for Portland, there will be no criminal in the country not aware of it. It will be like a K mart blue light special for criminals. Any dreams of " the locals are not bad so it won't be a problem" are sadly mistaken when others find out. You can also be sure people like the proudboys and other such groups will intentionally target worse than ever so when they know they cannot be arrested and put out callouts for everyone else to do so as well. Makes you wonder if that wasn't what Trump has them on standby for. If this was some area no one cared about it would be one thing, but it is not and unless you make sure you actually have EXTRA forces on hand during any sort of reformation, then expect it to be ugly for a while. If you have a lack of police, if gangs come through to your neighborhood, you would either have to be prepared to fight them yourself of flee as they were forced to do so on the reservation when this happens and expect to come back to your home destroyed, possessions looted.
Any attempts to defund or disband will be intentionally sabotaged by Trump and his cronies to "Make an example out of Portland".
