Despite its rapid pace, the advance toward Mosul has been relatively uneven. Elite Iraqi special operations forces arrived at the city's outskirts before the rest of the coalition, which also includes tribal militias and the federal police. According to the battle plan, the advance into Mosul itself was to have begun only once the Iraqi army had converged on the city from three sides. Nonetheless, Prime Minister Haider al-Abadi reportedly ordered the special operations forces to continue on to the city, hoping to sustain the advance's momentum and prevent the Islamic State from using a pause in the fighting to regroup. Furthermore, though the original strategy provided for an avenue of escape to the west of Mosul , the Iraqi government allegedly bowed to pressure from Tehran in late October and allowed the Iranian-backed Popular Mobilization Forces to close it.