Security officials in Europe are concerned the Syrian civil war could lead to jihad in their countries.
Many Islamic radicals traveled from Europe to Syria to fight in the war and some are now coming home.
In Germany, authorities arrested a man they believe fought for a hard-line Islamic group in Syria.They suspect he was planning an act of violence.
Meanwhile, Spanish and Moroccan police arrested seven suspected members of a cell that allegedly recruited jihadists to fight in Syria and other places.
Last year, Spanish police arrested eight suspected jihadist militants in a similar operation.