Generally countries are doing ok job blocking extremist from immigrating but preventing kids of those immigrants from radicalizing is hard to impossible. Police

Generally countries are doing ok job blocking extremist from immigrating but preventing kids of those immigrants from radicalizing is hard to impossible. Police struggle to penetrate insular immigrant communities and political environment (for now) prevents harsh measures against even known terrorists (case in point - https://www.reuters.com/article/us-canada-guantanamo-khadr-idUSKBN19P203 https://www.reuters.com/article/us-canada-guantanamo-khadr-i...) UK, France and Germany each had more than 1000 citizens fighting for ISIS in Syria and Iraq - most of them are second gen. Most of terrorist in French terrorist attacks on 2015 were citizens of EU and second gen immigrants. I would expect situation to get much worse in the next 20-30 years unless global Islam looses steam and purpose similar to Christianity loosing them earlier in 20th century.