Sir Simon Mayall, Prime Minister David Cameron's security envoy to Iraq, tells Nick Robinson that the fall of Mosul is a major defeat for IS but there is more hard fighting ahead.
He adds: "This is the time for very heavy diplomacy if we have the courage for it."
Iraq's former national security advisor and Baghdad MP Mowaffak Al-Rubaie said: "The next phase in the struggle against Islamic State is an intelligence capacity building... The next war is an intelligence led war, not army versus army."
(Image: Soldier waves Iraq flag; Credit: Getty Images)