that considers all foreigners/nonwhites to be their enemy. This is really not illogical or insane at all. And attacks like this are hardly "isolated incidents", they are symptomatic of deeper undercurrents in American society which cannot really be talked about openly. You would understand this if you lived in the United States for a while.
By the same token, the various media and government attempts to portray the Norwegian Breivik as "insane" is merely a BS attempt to downplay and deflect attention away from anti-Muslim/anti-immigrant sentiment. These people are not crazy at all, they know perfectly well what they are doing and they are acting on their sincerely held political beliefs.
I don't believe that these Sikhs were mistanekn for Muslims, but rather I believe that they were simply killed for being Sikh. In the United States Sikhs are just as foreign as Muslims are, and therefore they are considered as a threat. Chinese in this country should take note of this.