Open this photo in gallery: Workers install a giant Serbian flag reading 'We are not a genocidal nation' on a building in Belgrade, on May 22.OLIVER BUNIC/Getty Images The leader of Bosnia’s Serb-controlled territory reiterated a threat to secede from the Balkan country Wednesday, a day ahead of a U.N. vote on establishing an annual day to commemorate the 1995 genocide of more than 8,000 Bosnian Muslims by Bosnian Serbs. Relatives of the victims, meanwhile, said that the vote would mark a historic day in ensuring that the deaths cannot be denied or forgotten. The proposed U.N. resolution sponsored by...