What many of the commentators fail to recognize is that the individual involved in the Edmonton incident has been in Canada for five years.  This suggests a likelihood that he was radicalized sometime after his arrival in Canada, the point being that this is more a radicalization issue than an immigration issue. To keep things in perspective well over a million people migrated to Canada in those five years including tens of thousands refugees. I also find it interesting that Trump brings up this one incident while glossing over the tens of thousands of Americans who have been killed by guns in that time, many of whom were killed in mass shootings.