Not to sound glib, but we're a bit used to extremist attacks here in London. To have read about a bombing on Drottninggatan came as a shock, although it's interesting the suspect in yesterday's attack lived in England for a period.
In hindsight, though, maybe I shouldn't have been surprised. Immigration, especially from Muslim countries, is a hot issue all throughout northern Europe. The Sweden Democrats, a nationalistic, anti-immigrant party, made significant gains in the recent elections.
Sweden prides itself on being a tolerant and accepting society. However, the recent influx of immigrants, and the response to it by a significant segment of the population, is placing the country's self-image under a stern test these days.