Mosul, Iraq
© AFP 2016/ MARWAN IBRAHIM
More than 400 additional US troops have arrived in Iraq in recent days as the battle for Mosul is expected to begin soon, a US defense official said Thursday.

Operation Inherent Resolve spokesman Colonel John Dorrian stated that there are 4,460 US troops in Iraq, compared to 4,000 a week ago, and that Iraqi security forces are preparing to reclaim Mosul. Dorrian did not specify what the US troops would be doing, but mentioned that they were setting up a logistics hub at the recaptured Qayyarah airbase to the south of Mosul, which will serve as a staging area for Iraqi forces.

Mosul, the second largest city in Iraq, was seized by Daesh two years ago. Since that time the violent extremist group has lost much of its territory in Iraq and Syria, but has retained control over Mosul and Raqqa.

Dorrian stated that Iraqi forces would determine the time of the assault. General Joe Votel, the head of the US military's Central Command, last week suggested that Mosul could be reclaimed by the end of the year.

Saad al-Hadithi, spokesman for Iraqi Prime Minister Haider al-Abadi said, "The date will not be announced before the start of the operation for security reasons. There is no determined date for launching the Mosul operation." Further territorial advances on Daesh positions were slowed as supporting forces, including police and allied militants, appeared to require additional training.

According to Lieutenant General Vincent Stewart, director of the US Defense Intelligence Agency, the Mosul operation could be initiated in two or three months and the operation would be long and difficult. Mosul is one of the last areas in Iraq occupied by Daesh. Aware of the weakness of their position, Daesh extremists have reportedly been killing inhabitants and destroying cultural artifacts.

At least 3,000 Daesh fighters are said to remain in the city, of which a third is "the hardest-core" group, according to Gen. Townsend. He adds that retaking Mosul will be difficult to achieve quickly.

The battle is anticipated to be especially challenging as the one million citizens in the city are feared to be in danger of being used as human shields. Iraqi warplanes dropped some one million leaflets over as-Sherqat asking civilians to stay indoors and not get close to Daesh sites, said a Kurdish official, according to Asharq Al-Awsat.