Meanwhile over in France, there is a very large Muslim population, and there are thousands of mosques.  However, the French police raided and shut some of those mosques.  See article: "France's Disappearing Mosques"  quote: "Twenty of France’s 2,500 mosques and prayer halls have been shut down since December for allegedly preaching a radical interpretation of Islam. "  (the Atlantic website).  So there are places in the Western world where Muslims are being radicalized. How to know?  A doctor might look for symptoms of a problem.  An engineer might do tests to see if things are working as intended.  A Canadian Security Intelligence Service might look for telephone calls and e-mails, but what if leaders only communicate by speaking directly to their audience?