In the NL., home to 1 million Muslims, a spokesman for the Dutch intelligence service says it believes as many as 20 different hard-line Islamic groups may be operating in the country.

The last time Myriam Cherif saw her son Peter, 23, was in May 2004, when the two of them stood at the elevator on the fifth floor of the gritty public-housing project where they lived, just north of Paris. Myriam, 48, was born in Tunisia, moved to France when she…