A quote from Eliane Sciolino and Hélène Fouquet in The New York Times, 9 October 2005

[Belgium] in recent years has become the destination of choice for many French-speaking immigrants who are put off by France's intrusive security and intelligence services and tougher laws.

[...] "Belgium has become a logistical base for these people," said Didier de Quévy, a defense lawyer who has been involved in terrorist cases in the past and is
representing one of the defendants. "They have come here because the
penalties have been light."