Germany has been one of the most welcoming countries to immigrants and refugees from a war-torn Middle East. But has this approach left the European nation vulnerable to attack? On Monday, a truck plowed into the crowd at a Christmas market, killing twelve and injuring dozens more. The main suspect is a man in his early twenties who was already known to German authorities as a potential terrorist. Are these types of attack an inevitability in today’s world? Or could this attack have been prevented with more stringent immigration policies?