What I mean is that when confronting a violent crowd, how can the police control them from making damages, in the most appropriate psychological manner?
I will pass your question to our experts, but meanwhile I can share some of my personal observations on the subject:
1. Visible police documentation: in some cases, a police officer holding a camera has a better calming effect on a crowd than one holding a baton or even a gun. This will usually work best if the crowd hasn't become actively violent, but is on the verge.
2. Isolation: break the crowd into small groups, preferably into isolated individuals. The goal is to get the rioters out of 'herd mentality' and back into individual thinking. It can be achieved by various methods.
3. Apprehending of agitators: removing the most visible and audible members of the crowd mught have a calming effect on it. This is a rather risky tactic, as it might incite further violence.
Hope this helps!
Shlomi Chetrit's comments above are supported by global practices.
Many progressive agencies now have an established protocol for the escalation of force, that starts with the mere presence of police, and the use of "soft" tactical gear (baseball caps, no shields, open hands, etc,) with a focus on communications and engagements. As Shlomi stated above, these strategies are applicable before the onset of violence.
The identification and apprehension of agitators can go far to deflating a crowds energy, again, defined protocols about how to do this are critical. Many agencies now use a specifically defined (and training) team that is tasked with moving into a crowd and quickly and safely securing the identified agitator in order to reduce the crowds volatility.
Jurisdictions that have hosted WTO and G20 meetings have found that a consistent group of agitators with an evolving strategy have moved from city to city hosting these meetings, and their strategies have shifted to avoid effective police response. However, dedicated intelligence gathering and effective organizational training have gone far in recent years to prevent serious injury and loss of life. Unfortunately, adequate preventive policing measures are usually not practical (or politically expedient) in many liberal democracies and as a result, trying to prevent the occurrence of any damage or loss of property has proven to be an elusive goal for police agencies at such events to date.