BAGHDAD/ERBIL: In the early days of the assault on Islamic State in Mosul, Iran successfully pressed Iraq to change its battle plan and seal off the city, an intervention which has since shaped the tortuous course of the conflict, sources briefed on the plan say. The original campaign strategy called for Iraqi forces to close in around Mosul in a horseshoe formation, blocking three fronts but leaving open the fourth – to the west of the city leading to Islamic State territory in neighbouring Syria. That model, used to recapture several Iraqi cities from the ultra-hardline militants in the last two years, would have left fighters and civilians a clear route of escape and could have made the Mosul battle quicker and simpler. But Tehran, anxious that retreating fighters would sweep back into Syria just as Iran’s ally President Bashar al-Assad was gaining the upper hand in his country’s five-year civil war, wanted Islamic State crushed and eliminated in Mosul. The sources say Iran lobbied for Iranian-backed Popular Mobilisation fighters to be sent to the western front to seal off the link between Mosul and Raqqa, the two main cities of Islamic State’s self-declared cross-border caliphate.