08/11/2016 12:25 PM AEDT | Updated 08/11/2016 9:06 PM AEDT

The Fight For Mosul: Coalition Hits IS Stronghold Of Bashiqa

The offensive to take Mosul has stretched into a fourth week.

Azad Lashkari / Reuters
Military vehicles of Kurdish peshmerga forces roll towards Mosul.

The fight to take Mosul has entered its fourth week, and shows no sign of letting up.

The 100,000-strong US-backed alliance launched the offensive to take the IS-held stronghold in northern Iraq on October 17, with Iraqi security forces, Kurdish peshmerga and Shi'ite fighters making painfully slow progress towards the city.

It remains unclear how long it will take for the coalition to drive IS out of Mosul, Iraq's second-largest city, where Islamic State has been in control since 2014 and where there were reportedly around 5,000 IS militants prior to the start of the military push.

Here's what we know about the military operation -- and the unfolding human tragedy -- so far.

The latest

Overnight, hundreds of Kurdish fighters advanced into Bashiqa to the east of Mosul, entering the town and exchanging heavy fire with IS fighters, according to media reports.

The ground assault on the largely deserted town was spearheaded by Kurdish armoured columns backed by US-led airstrikes. The Kurdish forces, known colloquially as peshmerga, have had Basiqa in their sights for weeks but the overnight assault is the most serious effort to wrest the town from IS so far.

Meanwhile, Iraqi soldiers have also been pushing towards Hamam al-Alil, to the south of Mosul, discovering a mass grave containing 100 decapitated bodies in the process.

The human cost

Officials and NGOs have been warning that the effort to rid Mosul of IS will likely cause a high civilian death toll. And while reliable estimates on civilian casualties are hard to come by, numerous recent tragedies have pointed to a growing number lives lost.

Earlier this month, 8 civilians from a single family were reportedly killed by a US airstrike outside Mosul and in late October the Iraqi air force were said to have killed 13 mourners at a mosque.

The Guardian wrote at the time: "The deaths are intensifying concerns about risks to ordinary Iraqis now trapped in the city. Officials and aid agencies have been warning for months that the effort to dislodge Isis from their last major stronghold in Iraq could have a high humanitarian cost".

On the military side, the Iraqi forces do not issue death tolls and it's unknown how many IS fighters have been killed.

However, it's reported that military casualties are on the rise as the coalition moves closer to Mosul. The Associated Press reports: "The troops are suffering casualties as the militants target them with suicide car bombs and booby traps in close-quarters fighting along the city's narrow streets."

Where to from here?

The anti-IS coalition's extremely slow progress towards Mosul is likely to continue if IS, as is expected, decides to dig in and defend the city.

"If that is how the war develops, then the most likely pattern will be for slow progress by Iraqi forces in the coming weeks, backed up by intensive use of air power and artillery support by coalition forces," the University of Bradford's Paul Rogers wrote for The Conversation UK on Tuesday.

Rogers says another factor hampering the coalition's progress are the guerrilla tactics being used by IS, which has seen them avoid direct fighting with the better equipped coalition.

"IS tactics have so far been mainly to avoid direct confrontation ... using a wide array of indirect fire attacks, suicide bombers and snipers," he added.

The slow progress has been exacerbated as special forces troops pushed into more densely populated areas in and around Mosul, the Guardian reports.

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