Fresh advance in east Mosul to begin within days: US commander

Iraqi forces will resume their push against the Islamic State (IS) group inside Mosul in the coming days, a US battlefield commander told Reuters on Monday.

The fresh advance will be a new phase in the two-month-old operation that will see American troops deployed closer to the front line in the city, he said.

The battle for Mosul, involving 100,000 Iraqi troops, members of the Kurdish security forces and Shia militiamen, is the biggest ground operation in Iraq since the US-led invasion of 2003. The upcoming phase appears likely to give American troops their biggest combat role since they fulfilled President Barack Obama's pledge to withdraw from Iraq in 2011.

Quarter of Mosul under Iraqi control

Elite Iraqi soldiers have retaken a quarter of Mosul, the militants' last major stronghold in Iraq, but their advance has been slow and punishing. They entered a planned "operational refit" this month, the first significant pause of the campaign.

A heavily armoured unit of several thousand federal police was redeployed from the southern outskirts two weeks ago to reinforce the eastern front after army units advised by the Americans suffered heavy losses in an IS counter-attack.

US advisers, part of an international coalition that has conducted thousands of air strikes and trained tens of thousands of Iraqi ground troops, will work directly with those forces and an elite Interior Ministry strike force.

"Right now we're staging really for the next phase of the attack as we start the penetration into the interior of east Mosul," Lieutenant Colonel Stuart James, commander of a combat arms battalion assisting Iraqi security forces on the southeastern front, said in a Reuters interview late on Sunday.

"So right now, positioning forces and positioning men and equipment into the interior of east Mosul... it's going to happen in the next several days."

That will put US troops inside of Mosul proper and at greater risk, though James said the danger level was still characterised as "moderate". Three US servicemen have been killed in northern Iraq in the past 15 months.

James, speaking from an austere outpost east of Mosul where several hundred US troops are stationed, said the pace of the upcoming phase on the eastern side would depend on resistance by IS, also known as ISIS, ISIL or Daesh.

"If we achieve great success on the first day and we gain momentum, then it may go very quickly. If Daesh fights very hard the first day and we run into a roadblock and we have to go back and go OK that was not the correct point of penetration, it may take longer," he said.

Further integration with the Iraqi troops - to what commanders described as an unprecedented level for conventional US forces - will help synchronise surveillance, air support and force movement, according to James.

"It increases our situational understanding. The man on the ground knows what's going on best," he said. "It's just better when they're on the ground talking to each other and saying, 'Hey, have you looked at that area over there? That's decisive terrain. Have you thought about putting forces there?"

Fall of Mosul to end IS ambitions

Mosul, the largest city held by IS across its once vast territorial holdings in Iraq and neighbouring Syria, has been in the group's possession since its fighters drove out the US-trained Iraqi army in June 2014.

Its fall may end IS's ambition to rule over millions of people through a self-styled caliphate, but the fighters could still mount a traditional insurgency in Iraq, and plot or inspire attacks in the West.

A multi-ethnic city where as many as 1.5 million of a pre-war population of about 2 million are still thought to be living, Mosul is divided roughly in half by the Tigris River. The western section, which Iraqi forces have yet to penetrate, has built-up markets and ancient narrow alleyways that will complicate future advances.

Iraqi Prime Minister Haider al-Abadi had said he would win Mosul back by the end of this year, a deadline now certain to be missed. His commanders say their advance was held up by the need to protect civilians, fewer of whom fled than initially expected.

Inclement weather has repeatedly delayed ground advances that rely heavily on aerial surveillance and air strikes.