Stocktrek Images/Thinkstock(MOSUL, Iraq) — Iraq’s announcement of the start of the offensive to retake Mosul from ISIS is a pivotal moment in defeating ISIS, which has made the city its de facto capital in Iraq since seizing it in mid-2014.
The Iraqi offensive on Mosul is the culmination of a two-year Iraqi military campaign to remove the ISIS military threat from northern Iraq.
Much of the U.S. military presence in Iraq during that time has been geared toward training and advising Iraq’s security forces to defeat ISIS militarily and take back the cities controlled by ISIS, particularly Mosul. So far, 35,000 Iraqi troops have been trained by the U.S.-led coalition, including the eight to 12 Iraqi army and Kurdish Peshmerga brigades that have been slotted for the offensive on Mosul.
What the Offensive on Mosul Will Look Like
The offensive will be an Iraqi and Kurdish military operation assisted by American advisers working in various Iraqi military headquarters. American and coalition aircraft will provide airstrikes in and around Mosul much as they have for several months in preparation for a large ground offensive. However, American special operations forces might come close to combat situations as they assist Iraqi special operations forces engaged in the fight.
ISIS fighters inside Mosul have been preparing elaborate defenses for months in anticipation of the offensive. What is unknown is how stiff a defense ISIS fighters will put up to defend the city. They could cede some parts of the city willingly, as happened in Jarabulus, or put up stiff resistance in other parts of the city, as they did in the battles for Manbij and Ramadi.
ABC News takes a look at why Mosul is so important in the fight against ISIS.
What Is Mosul?
Located along the banks of the Tigris River in northern Iraq’s Nineveh Province, Mosul is Iraq’s second largest city with a population of more than 2 million residents. The population represents a mix of the diverse ethnic groups in northern Iraq, though the majority are Sunni Arabs and Kurds. It is believed there are currently 1 million residents in the city.
Mosul is the main industrial city in northern Iraq and a vital transportation hub in the flow of goods to and from Turkey and Syria. It is also located near significant oil fields in northern Iraq and the major oil pipeline into Turkey.
ISIS surprisingly seized Mosul in June 2014 in a matter of days after the retreat of a large number of Iraqi security forces from the city. American officials have blamed that retreat on the Sunni Arab soldiers and police based in the city who abandoned their posts after growing disenchanted with the increasing sectarianism of the Shiite-led government of Iraqi Prime Minister Nouri al-Maliki.
The city’s capture left ISIS with large amounts of Iraqi military equipment and supplies that it quickly used to push toward the Iraqi capital of Baghdad, 250 miles to the south. ISIS also seized an estimated $500 million in cash taken from the Central Bank of Mosul that it has used to fund its military and terror operations.
Why Is It Important to Retake Mosul?
ISIS’s seizure of Mosul was a blow to Iraq’s political stability and a propaganda coup for a terror group that wanted to demonstrate it was gaining territory to establish a new caliphate.
A successful offensive on Mosul will take away from ISIS its last strategic stronghold in Iraq and end the territorial dominance it commanded over large areas of northwestern Iraq for the past two years.
The group’s control of territory there was made easier by the flow of ISIS fighters from its de facto capital of Raqqah in north central Syria. An ISIS defeat in Mosul would cut off that route and leave the terror group’s military operations effectively contained to Syria.
What Is the Iraqi Military Plan for Mosul?
For more than two years, the Iraqi military offensive on Mosul has been expected to be the most important battle against ISIS.
Much of the training of Iraqi and Kurdish security forces by American and coalition trainers has effectively been directed at generating the more than 25,000 troops believed needed for an offensive on Mosul.
From early on, American military officials have telegraphed that the city would be enveloped from the north and south by as many as eight Iraqi Army brigades and two Kurdish Peshmerga brigades.
Enveloping the entire city might take some time as it did in the previous Iraqi military offensives on Ramadi and Fallujah. Once that was completed elite Iraqi special operations forces known as the Counter-Terrorism Service will push into the center of the city to drive out ISIS.
The expectation has always been that ISIS would mount a stiff defense to hold the city with the possibility of fierce street-to-street fighting on a grand scale.
If Iraqi forces successfully retake the city, plans call for as many as 6,000 local Iraqi police to quickly step in to help establish order.
When the fighting begins, it is believed that as many as 800,000 civilians could flee the city. As part of its planning, the Iraqi government has worked with the United Nations and international relief organizations to build 20 camps to take care of them.
As was done in the battles for Ramadi and Fallujah, the Iraqis will put in place screening procedures to find any ISIS fighters disguised as civilians fleeing the city.
Then the thousands of Iraqi military forces that fought to retake the city will undergo new training by the coalition in counterinsurgency techniques as ISIS likely morphs away from a combat force into an insurgent role.
ISIS Prepares to Defend Mosul
The U.S. military estimates that there are between 3,000 and 4,500 ISIS fighters still inside Mosul. For months they have readied themselves for the offensive in preparation for a tough urban fight.
They have built built berms and trenches along the major roadways into the city and placed booby-trapped bombs along roads, bridges and inside buildings. Giant pits of tire and oil have been readied to create giant dark clouds that would make it difficult for coalition aircraft to conduct airstrikes in the city.
They have also placed restrictions on the local population to conceal their operations in buildings like hospitals, schools and mosques that coalition aircraft are not allowed to strike.
“All these things cause delays and challenges,” Colonel John Dorrian, the U.S. military spokesman in Baghdad, told Pentagon reporters this week. “But they’re also things that as we train the Iraqis to go into Mosul, a lot of them have received specialized training like explosive ordnance disposal, sniper training, breach training, and there have been warfare-trained so they know how to clear buildings and all these sorts of things.”
It is believed some senior ISIS fighters have already left Mosul ahead of the expected Iraqi offensive and a Pentagon spokesman characterized those that have remained as “a demoralized enemy.”
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