Iraqi troops have cleared the Islamic State from most of eastern Mosul and are now shifting their gaze across the Tigris River. Reaching the city's western half will not be easy, though. Five bridges span the river running through the heart of Mosul, all of which have been have severely damaged by U.S. airstrikes. Further sabotage by the Islamic State has rendered the structures almost impassable, making any attempt to cross the river a risky undertaking for Baghdad's beleaguered forces.
The U.S. Air Force initially targeted the bridges to prevent the Islamic State from crossing the Tigris River as Iraqi forces pushed through eastern Mosul. The operation succeeded in reducing the amount of men and materiel the jihadist group was able to dispatch to its fighters on the eastern bank, cutting off much-needed vehicle-borne improvised explosive devices, reinforcements and supplies. Despite the level of firepower brought to bear, the United States made sure to disable the bridges in a way that allows them to be easily restored. This was achieved by striking the more accessible portions located on land.
Based on recent satellite imagery, the Islamic State has not taken the same precautions. Instead the group has focused its efforts on damaging the bridge sections spanning the river itself, where construction crews would have a harder time reaching and repairing them. The jihadists have also begun demolishing the bridge pilings on the western bank, which will force Iraqi troops to cross the river to repair the wreckage. At the same time, the Islamic State has built up its battlements and trenches, peppering Iraqi troops with mortar fire to disrupt their preparations to strike out across the river. These measures will make transiting the Tigris — already a dangerous endeavor in the city's urban terrain, where the eastern bank rests at a lower elevation than its western counterpart — even more treacherous.
Iraqi forces do have other approaches on western Mosul — for instance, they could advance on the area from the south and west. But no alternative route is ideal, considering Baghdad's troops are massed in the city's eastern half. Nor has the Islamic State neglected to protect itself: The group has already set up defensive positions on its southern and western flanks. Although conquering eastern Mosul is a great victory for Iraqi security forces and the government in Baghdad, achieving a similar win in the city's west will come at a high price.