In-depth: As east Mosul is cleared of Islamic State group fighters, Iraqi troops survey the shoreline with crucial vigilance, writes Gareth Browne.





Now efforts are being recalibrated to the city's west bank - where, as has been widely reported, the challenges that coalition forces will likely face are unique.



The city of Mosul is severed from north to south by the River Tigris, and its western half is far more densely populated than its east - rendering the potential for civilian casualties much greater. The west is also home to the narrow streets of the old city, and tightly packed housing will reduce the advantage of the government's armoured vehicles and tanks, not to mention their air power.



Both of these were indispensable advantages in the city's east.



Before any real efforts can be made to recapture the remainder of the city, Iraqi forces must first deal with the river itself. A combination of coalition airstrikes and IS vandalism has left all five of the city's bridges inoperable. Every night they are coming in boats, sometimes dozens, on suicide missions. Normally we get them before they reach our side of the river, but not always



Recent days have seen the Iraqi army begin construction of several floating bridges, while heavy hardware has also been moved to the southern town of Qayarrah in anticipation of an assault on west Mosul from the south.



As it stands, Iraqi government troops have also taken up position along the river's east bank. But the natural barrier the river serves as has done little to reduce the danger posed to the army's 16th division by IS militants.



"Every night they are coming in boats, sometimes dozens, on suicide missions. Normally we get them before they reach our side of the river, but not always," warns Colonel Nazer Tahir of the division's 75th Brigade. Article continues below Attending to the corpses of IS fighters puts Iraqi soldiers at risk from snipers on the west bank of the river [Gareth Browne]



He looks out towards the river from the rooftop of a house which now serves as his unit's forward-most position.



This fortified post sits just south of the city's now disabled fourth bridge, in the al-Ba'ath neighbourhood. It has had some very close calls - just days ago a ground floor window was shattered by an IS-launched RPG. Nobody was hurt.



The bodies of IS fighters who succeeded in sneaking across the river can also be seen lying little more than 20 metres from the house.



Despite the entire east bank having been officially declared "liberated", there remains a 600m stretch of no-mans-land between this house and the Tigris.



This boggy stretch is well within the range of the many IS snipers on the river's west bank, preventing Iraqi soldiers from pushing right up to the shoreline. Since losing control of the city's east, IS has taken to launching daring, even suicidal, night-time raids across the river under the cover of darkness.



Small boats packed with as many as a dozen fighters try to cross the river at its narrowest point, but most are picked off by the army's gunners who are on constant look out.

Article continues below Iraqi soldiers must attempt to spot IS fighters navigating

through this maze of buildings on the east bank of the Tigris [Gareth Browne] After more than three months of fighting, Iraqi government forces have announced the liberation of Mosul's entire eastern half. Much of the fighting had been fierce, with Iraqi officers claiming to have killed more than 3,300 Islamic State group fighters.Now efforts are being recalibrated to the city's west bank - where, as has been widely reported, the challenges that coalition forces will likely face are unique.The city of Mosul is severed from north to south by the River Tigris, and its western half is far more densely populated than its east - rendering the potential for civilian casualties much greater. The west is also home to the narrow streets of the old city, and tightly packed housing will reduce the advantage of the government's armoured vehicles and tanks, not to mention their air power.Both of these were indispensable advantages in the city's east.Before any real efforts can be made to recapture the remainder of the city, Iraqi forces must first deal with the river itself. A combination of coalition airstrikes and IS vandalism has left all five of the city's bridges inoperable.Recent days have seen the Iraqi army begin construction of several floating bridges, while heavy hardware has also been moved to the southern town of Qayarrah in anticipation of an assault on west Mosul from the south.As it stands, Iraqi government troops have also taken up position along the river's east bank. But the natural barrier the river serves as has done little to reduce the danger posed to the army's 16th division by IS militants."Every night they are coming in boats, sometimes dozens, on suicide missions. Normally we get them before they reach our side of the river, but not always," warns Colonel Nazer Tahir of the division's 75th Brigade.He looks out towards the river from the rooftop of a house which now serves as his unit's forward-most position.This fortified post sits just south of the city's now disabled fourth bridge, in the al-Ba'ath neighbourhood. It has had some very close calls - just days ago a ground floor window was shattered by an IS-launched RPG. Nobody was hurt.The bodies of IS fighters who succeeded in sneaking across the river can also be seen lying little more than 20 metres from the house.Despite the entire east bank having been officially declared "liberated", there remains a 600m stretch of no-mans-land between this house and the Tigris.This boggy stretch is well within the range of the many IS snipers on the river's west bank, preventing Iraqi soldiers from pushing right up to the shoreline. Since losing control of the city's east, IS has taken to launching daring, even suicidal, night-time raids across the river under the cover of darkness.Small boats packed with as many as a dozen fighters try to cross the river at its narrowest point, but most are picked off by the army's gunners who are on constant look out.