Wikipedia:Use Ethnic Epithets

Sometimes it is a good idea to clarify the background of a source by using ethnic epithets. Such situations occur frequently when there is antipathy between two nationalities. For example, when a war is going on between Country X and Country Y, there is a high danger that commentators from the warring countries are biased in what they say. In such a case, the nationality of the source should be mentioned to warn the readers about this.