Iraq has seen the use of better tactics and training by American military police (MPs). Much of this was the result of recent experience in the Balkans. One of the more useful new tactics developed from this experience was how to "deflate" an angry mob. Most demonstrations that get out of hand are organized and led by a handful of mob leaders. In past times, these guys were called "agitators." That's an apt description. But the agitators don't strictly control the mob, they simply "agitate" it. MPs have learned that a mob can often be "deflated" by having skilled (usually older and more experienced) MPs engage members of the mob in discussion. This can be in the guise of negotiations (about where the mob can go, or about their grievances) or simply friendly discussion. Even when conducted through interpreters, this usually gets the friendly attention of many members of the mob. Special Forces troops are good at this, as they usually speak the local language and already know local leaders. If you keep these discussions going on for an hour or so, the mob losses it's enthusiasm for violent action and starts to break up, or "deflate." If you can't do it with words, you go to plan "B", which means identifying the agitators and plunging in with some burly MPs (in a diamond formation) and arresting these mob leaders. This may inflame the mob momentarily, but once the agitators are gone, so is the agitation, and the mob usually deflates. 

Sometimes equipment can be used as well. Helicopters hovering low over a mob, especially in a dry and dusty environment, stirs up a storm of dust, sand, wind and noise. This often works. If you have an M-1 tank, back it up into the mob. The hot gasses coming out of the M-1s 1500 horsepower gas turbine engine forces civilians in its path to get out of the way. The bulk of the advancing tank also makes a fearful impression.