Breivik carried out a bomb and shooting attack in Oslo that killed 76 people. He could be an example for others, but Belgian intelligence services are determined to avoid this.
Claude Moniquet, an expert in the fight against terrorism, explains: "Many supporters of extreme-right ideas are frustrated. Breivik has built himself a so-called worldwide reputation. This could inspire someone who is mentally unstable and who also wants to leave his mark."
Detectives are focusing on people who behave suspiciously. "Someone who leads a lonely life in an apartment and next orders a couple of tons of chemical fertilizer, that's strange. We have to look at small details which could give us a hint."
Mr Moniquet does not want to cause panic. Chances are small that it also happens in Belgium, but is not impossible. "It's part of globalisation. Some want to copy certain behaviour and also become famous. They think they have a message to spread. They kill people in a shopping centre, on a train, or in a youth camp. We should be on the alert."