An enormous amount of research goes into this
Generally on Crowd Psychology. There are certain points in the behaviour of crowds that, if not responded to, cause the protest to escalate into a riot. If you watch, you see it's one person who moves forward to sit down, and a V-shape of people follow him. The actions prove to be innocent, but it's that manner in which people in a crowd operate that lead to stone-throwing and Molotov cocktails; it only takes one person.
An aerial commander, given two seconds' choice, will order the front line (who aren't even in riot position anyway) to make a 10m charge forward, to break the crowd's confidence. That's all. Scare tactics, to stop the surface tension bubbling over into violence.
If the crowd DID escalate, you'd see a solid line of officers and a spearhead technique to go in and remove the two or three agitators inside the protest who are stirring up the crowd.
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Grrrmachine the indifference engine, Mon 28 Jun 2010, 7:55,
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Ahhh, the old 'punch them before they punch you' style of drunken pub logic.
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OneSullenBrit *air sandwiches*, Mon 28 Jun 2010, 10:01,
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