this is bbc news. the headlines: hundreds of suspected criminal gangs have been arrested following a worldwide sting operation organised by the fbi. gangs were tricked into using what they thought was a secure messaging app, which was developed by the authorities, who were then able to monitor messages about drug dealing and planned murders. the former bosnian serb commander ratko mladic is to spend the rest of his life behind bars after losing his appeal against a genocide conviction. the judges upheld the life sentence handed down four years ago for atrocities during the break up of yugoslavia, including the srebrenica massacre in 1995. the us military and troops from other western nations are facing a new threat in iraq. american airbases have come under attack from iranian—made drones fitted with explosives. it follows earlier rocket attacks on western forces but commanders say the drones are a game—changer. iran denies involvement.