Sinan Selen, a 46-year-old Istanbul-born counter-terrorism expert, will be the first Muslim to fill a top leadership position within Germany's intelligence community. Throughout his government career, Selen has been resolute in confronting Islamic fundamentalists in Germany. He also led efforts at the Federal Office for the Protection of the Constitution (BfV) to monitor the Turkish nationalist Milli Görüs, an influential Islamist movement strongly opposed to Muslim integration into European society. The leadership changes at the BfV were spurred by a cellphone video that purportedly showed right-wing mobs attacking migrants over the murder of a German citizen in Chemnitz by...