ERBIL, Iraq - Once Islamic State is defeated, Iraq should be divided into three separate entities to prevent further sectarian bloodshed, with a state each given to Shi'ite Muslims, Sunnis and Kurds, a top Kurdish official said on Thursday.Iraqi troops have expelled Islamic State from some key cities the militants seized in 2014, and are advancing on Mosul, the largest city under IS control. Its fall would likely mean the end of the group's self-proclaimed caliphate.But even if Islamic State was eliminated, Iraq would still be deeply divided. Sectarian violence has continued for years and a power-sharing agreement in Baghdad has only led to discontent, deadlock and corruption.Masrour Barzani, head of the Kurdistan Regional Government's (KRG) Security Council and son of KRG President Massoud Barzani, said the level of mistrust was such that they should not remain "under one roof.""Federation hasn't worked, so it has to be either confederation or full separation," Barzani told Reuters in an interview on Wednesday in the Kurdish capital Erbil. "If we have three confederated states, we will have equal three capitals, so one is not above the other."