As the creeping erosion of this notion continues, police officers around the world are becoming convinced they are fighting a war on something or other, whether that's drugs, terror, anarchists or political subversion. This mindset contrasts with the public's unchanged perception of what the police should be doing, which is to keep the streets safe, a conceptual clash that can lead to unexpected results. Ukraine provides one recent example. On Nov. 30, the Berkut riot police beat up a few hundred students who had camped on the main square of the capital, Kiev, to call for closer ties between Ukraine and Europe. Ukrainians were not used to being treated like the population of a "colony of rule." Hundreds of thousands took to the streets the following day, setting off a chain of events that led to the overthrow of President Viktor Yanukovych and the current crisis on Europe's eastern borders.