President Recep Tayyip Erdogan threatened Friday to walk away from a deal that has substantially reduced the flow of migrants to the European Union and also effectively end Ankara's membership bid by bringing back capital punishment. Erdogan's warning he could open Turkey's borders to illegal migrants bound for Europe prompted an immediate objection from Germany that such "threats" were unhelpful. Greece, which would face a heightened influx of migrants if Turkey made good its threat, also expressed "concern" at what it said would be "an act of aggression." The Turkish leader's comments came a day after the European Parliament angered...