As Crawford Kilian has pointed out, regarding refugees coming to Canada: 
"The United Empire Loyalists were refugees. So were the Irish fleeing the potato famine of the 1840s and the black people escaping slavery in the American South. The Doukhobors were Russian refugees. We turned away the Jewish refugees on the St. Louis (“None is too many,” Ottawa decided). But we welcomed the Hungarians in 1956, the Vietnamese and the Ugandan Ismailis in the 1970s. No one worried about Communist spies and terrorists slipping into the country among them."
Now some Canadians want to pull up the drawbridge. 
Whether we like it or not, we’re in the midst of the greatest displacement of people in human history, and it will only get worse. There are 65 million displaced persons in the world. Canada has taken in 25,000 this year. Not exactly bragging rights.
Refugees have made this county what is today. They can be an asset, not a liability.