You're assuming the police actually WANT to de-escalate. They generally do not. (If you are suggesting the police in "far-left strongholds like Portland" behave or are motivated qualitatively differently than police in other cities... nope).

They want to scuffle, they want to punish people who have verbally antagonized or threatened them, or who they think deserve it; they want to protect challenges to their authority and maintain control of the situuation, or think they need to crack down hard to avoid a total social breakdown (the opposite of de-escalation) -- they have a variety of values and priorities, avoiding a "riot" is seldom one of them. ("Winning" the riot is).

Here in Baltimore, the last few months of protest had very little property destruction or scuffling. Some here wanted to credit the restraint or intentions of "proestors" -- I think it's far more likely that the police administrators this time, somehow, got the forces in the street to actually avoid escalation.

I am a middle-aged leftist who has been at many many protests. Every "riot" I have been near was initiated by escalation by police, including chemical weapons use, agitating the crowd to respond, bringing more response in turn. If the police avoid escalation, it doesn't happen. This isn't always what the leftist radicals want to admit either -- they may want to think it's "the people" who are in control of things, who are angry enough to rise up or something. In fact, it's the folks who are trained to act together, with the better weapons and the (usually) disciplined command and control structure, who have pre-existing relationships of working together as a team -- who largely determine whether to escalate or de-escalate -- and this isn't that surprising.

The police usually don't actually want to de-escalate, they want to knock heads. By "the police" I mean both the "white shirts" and the "blue shirts". Sometimes the decision-makers might have preferred not to escalate, but literally would not be able to control those they ostensibly control though; the police are there for a fight.

1. Left-right is a completely different axis to authoritarian-liberty. I’ve known both an anarcho-communist and an anarcho-capitalist.

2. The idea that the US Democrat party is “far-left” is hilarious from here in Europe.

> What’s the best way to stop them from starting? What de-escalation methods are proven to work?

The ELI5 answer is “political competence”. These are things that would take at least a degree module to understand fully, not a comment thread.

[0] https://www.nbcnews.com/storyline/dakota-pipeline-protests/d...

Tear gas has a similar problem: a tear gas cartridge in the face may blind you (or worse). Wikipedia says "As with all non-lethal or less-lethal weapons, there is some risk of serious permanent injury or death when tear gas is used. This includes risks from being hit by tear gas cartridges that may cause severe bruising, loss of eyesight, or skull fracture, resulting in immediate death. A case of serious vascular injury from tear gas shells has also been reported from Iran, with high rates of associated nerve injury (44%) and amputation (17%), as well as instances of head injuries in young people." [1]

1: https://en.m.wikipedia.org/wiki/Tear_gas