As Iraqi forces continue their campaign to uproot the "Islamic State" (IS) militant group from their stronghold in Mosul, questions have arisen concerning how the battle will play out, and who will be participating.

The peshmerga, the Kurdish military forces of Iraq known for their successes against the militant group, have announced they will hold back instead of joining Iraqi Security Forces as they enter the heart of the city.

DW spoke with Tomas Olivier, chief executive of the Netherlands-based security consultancy Lowlands Solutions and former senior officer at the Dutch defense ministry, to examine the ongoing campaign to uproot the militant group in Iraq.

DW: Why have the Kurdish peshmerga forces stopped advancing into Mosul given they are lauded as one of the best forces fighting IS?

Tomas Olivier: The leader of the peshmerga forces, Masoud Barzani, wisely stated about a week ago that peshmerga forces will not enter the city of Mosul and join the Iraqi army for the clearance operation aimed at liberating the city. Although close coordination between the peshmerga forces and the Iraqi army is in place, it has decided to focus on other pockets of resistance in northern Iraq and on the Kurdish-controlled city of Kirkuk, in which IS initiated a desperate campaign of violence in response to the advances of the Iraqi army towards Mosul.

In addition, the Kurdish peshmerga is far more focused on the Turkish army base in Bashiqa, on the outskirts of Mosul. In a statement, Barzani said he strongly opposes the participation of non-Iraqi elements in the liberation of Mosul. As such, Kurdish participation would not have been wise, to say the least.

What do Iraqi forces anticipate as they enter the next stage of liberating Mosul? Will it likely be block-by-block containment?

An urban, street-to-street combat scenario is most likely, especially due to the fact that IS elements have put up fierce resistance in some urban areas of Mosul. The US military estimates that the militant group has approximately 4,000 to 5,000 fighters inside the city. Therefore, the clearance operation will take several weeks, if not months. IS had months to prepare a network of defensive perimeters, tunnel systems and fortified positions in Mosul, and currently use a combination of small arms fire, anti-tank missiles and suicide bombers to block the advance of the Iraqi army.

In this case, the Iraqi army has to be extremely cautious in their approach to liberating the city, and to minimize casualties. Due to the risk of civilian casualties, the US-led coalition can only make use of precision munitions in the direct vicinity of the advancing Iraqi army. The street-to-street scenario is therefore the only practical and effective military option to clear the city of all of IS pockets of resistance.

How does this compare to previous operations?

The US-led coalition and the Iraqi army can't rely on air support due to the considerable risk of civilian deaths.

It's a classic example of traditional urban combat, in which the Iraqi army has to practice patience in order to be successful. Every neighborhood, every structure, every house, every building, every yard will have to be searched and cleared. Due to the fact that Mosul is a very large city, this will most likely, as I mentioned before, take months.

Is IS expected to hold ground or flee? How might this impact the operation?

Although there have been examples of IS deserters in the last couple of weeks, it is to be expected that the hardcore IS elements, still present in the city, will put up a fight and have no intention to "wave the white flag," so to speak. This is also due to the fact that many alleged deserters have been publicly executed by IS in the last couple of weeks.

A screening operation by Shiite forces, Iran-backed troops known as the Popular Mobilization Units, and Kurdish allies will cut off possible IS escape routes to the western and northern parts of the city. So it is to be expected that the Iraqi Army will not be facing a walk in the park, and will have to anticipate a slow, textbook-style military urban clearing operation.

What might the situation look like if and when Mosul is liberated?

The question of what happens after the liberation of Mosul is, without a doubt, the most prominent question that the international community, the US-led coalition and the Iraqi government is facing. Sunni Arabs historically controlled the northern Nineveh province; however, the region has numerous ethnic and sectarian groups.

So the risk to aggravate sectarian tensions is very present. This is the reason, for example, it was decided that the Iran-backed Shiite militias are not to enter Mosul. Another important factor will be the current developments between the Turkish and Iraqi government with regards to the presence of Turkish troops in the vicinity of Mosul, and the current build-up of armored Turkish columns at the Iraqi border.

Many inhabitants of Mosul felt alienated by the Shiite Arab-led Iraqi government. It is therefore not to be expected that the transformation will lead to a smooth unification of all these ethnic and sectarian elements after the liberation of Mosul. The real battle will therefore start on the day Mosul will be declared liberated.

This interview was conducted by Lewis Sanders IV.