Mr de Kerchove believes that EU states should work together more closely to prevent such atrocities: "I don't believe in large scale attacks like 9/11, but the EU should prepare for attacks by individuals eager to kill several people at the same time."
"Over 2,000 Europeans have fought or are eager to fight in Syria. Some have returned. This doesn't mean that they all want to commit atrocities, but some will. They have been trained with Kalashnikovs or light arms, possibly with explosives, but not for big attacks."
Mr de Kerchove continues: "I don't know if Nemmouche (the suspect of the Jewish Museum atrocity) was acting alone, but he did benefit from the free movement of persons across the Schengen zone. Member states should strengthen their co-operation and make better use of the information service of Schengen, Europol and Interpol."
The anti-terrorism czar calls for the introduction of a data base for air passengers, an initiative that is being vetoed by the European Parliament. He also urges the EU to help Syria's neighbours to ensure that radical groups do not gain control there.