When the police come to a protest dressed like that, armed, and expecting confrontation, both police and protesters start to think that a confrontation is inevitable. This was why, at the height of the often-violent protests of the 1970s, Washington, DC, police chief Jerry Wilson put cops in traditional police blues on the front lines, but kept his riot squad on buses parked on side streets—ready, but out of sight.
As a resident of Washington DC, I find this really interesting. I moved here in 2005 and I've generally been impressed with how well MPD has handled protests.
