People of Muslim faith have immigrated into US and North America for decades and we have accepted them here without any concerns.  It is the war in those countries, and the years of evil things that have been done in those countries that have created so much hate that there will be persons that will take vengeance on the west because they believe that we are the cause.  At the same time there is a radical people that declare publicly their intention to bring that terrorism world wide.  Yes there is a basis for all this....concerns.