Exiled Yemen president orders troops to Sanaa after predecessor killed

Yemen's exiled president ordered troops to advance on Sanaa hours after his predecessor was killed by Huthi rebels, while his son called for revenge.  President Abedrabbo Mansour Hadi called on Yemenis to unite against the Iran-backed insurgents who shot Ali Abdullah Saleh dead as he fled the city following the collapse of their alliance. "Let's join hands to end the control of these... criminal gangs and... open a new chapter to rid our beloved Yemen of this nightmare," Hadi, leader of the