A long-standing debate in Germany on how to handle migrants has intensified following deadly knife attacks in Solingen and Mannheim this year, prompting Europe’s largest economy to expand border controls despite protest from its neighbours. The Solingen suspect, a Syrian citizen, had evaded an order to be deported from Germany to Bulgaria, where he first entered the European Union. And an Afghan citizen is in custody following the Mannheim attack in May, which left a police officer dead. On September 16, Germany expanded controls to the frontiers of all nine of its neighbours in the hope of cu…