Following Sweden riots and Woolwich attack in the United Kingdom, the authorities have called for calm and restrain as evidence of reprisals are a possibility in Europe :
A possible backlash, Far right group English Defence League threatens 'feet on the street' in Woolwich :

1.  http://www.express.co.uk/news/uk/401807/Far-right-group-English-Defence-League-threatens-feet-on-the-street-in-Woolwich
2. Anti-Islamist protests flare following London attack
3. Woolwich attacks: Britain braced in case of far-right reprisals
4. MOSQUE ATTACKS AND EDL PROTESTS OVERNIGHT IN WAKE OF ...

5. Six admit planning to bomb English Defence League rally

Scandinavia :

1. Restaurant Torched in 4th Night of Sweden Riots
2. Sweden riots continue after police shooting

3. Højreekstreme demonstrerer efter brutalt London-drab

France : An important demonstration to take place Sunday May the 26th to oppose the Gay marriage could well give way to a street battle after the incidents that took place in the wake of the PSG football club championship victory that forced the Paris authorities to cancel a "victory tour".

1. « Woolwich :nous sommes en guerre », un éditorial de la Ligue de...