Iraqi security forces advance towards the western side of Mosul, Iraq on February 19, 2017. 

Smoke rises after members of the Iraqi rapid response forces fired a missile towards Islamic State of Iraq and Syria (ISIS) militants during a battle in the south of Mosul, Iraq on February 19, 2017. 

Smoke rises after a rocket landed in the middle of the Iraqi rapid response forces’ position during a battle against ISIS militants in the south of Mosul, Iraq on February 19, 2017. 

General view of a building of the University of Mosul destroyed during the battle with ISIS militants, in Mosul, Iraq on January 30, 2017.

Full library of University of Mosul burned by clashes during the battle with ISIS militants, in Mosul, Iraq on January 30, 2017.

A displaced Iraqi boy holds a white flag as his family flees during the battle between Iraqi rapid response forces and ISIS militants at Tigris river frontline between east and west of Mosul, Iraq on January 25, 2017.  

The Iraqi army gather after the liberation of a village from ISIS militants, south of Mosul, Oct. 21, 2016. 

A man who just fled Bazwaia village carries a white flag as he arrives at a special forces checkpoint, east of Mosul, Iraq, Nov. 1, 2016. 

An Iraqi forces vehicle advances towards Mosul during clashes with ISIS forces near the village of Bazwaya, on the eastern edges of Mosul, on October 31, 2016. 

Iraqi special forces neared the eastern city limits of Mosul on Monday, tightening the noose as the offensive to retake the ISIS stronghold entered its third week. 

A displaced Iraqi boy leads his animals to safety after escaping from the ISIS-controlled village of Abu Jarboa during clashes with ISIS militants near Mosul, Iraq November 1, 2016. 

Wounded Iraqi special forces soldiers react during clashes with ISIS fighters in Bartella, east of Mosul, Iraq, October 20, 2016. 

Iraqi special forces soldiers search a building located inside a church compound in Bartella, east of Mosul, Iraq October 21, 2016.

Newly displaced people wait to receive food supplies at a processing center for displaced people In Qayyara, south of Mosul, Iraq, October 21, 2016. 

A child rests among Iraqis fleeing violence in Mosul and internally displaced Syrians who fled ISIS controlled areas in Deir al-Zor, near the Iraqi border, in Hasaka Governorate, Oct. 23, 2016. 

Civilians return to their village after it was liberated from ISIS militants, south of Mosul, Iraq, Oct. 21, 2016.

Iraqis and internally displaced Syrians who fled ISIS-controlled areas in Deir al-Zor, buy food and water near the Iraqi border, in Hasaka Governorate, Oct. 23, 2016.

A displaced boy who was injured by a bomb attack in Mosul, is in Deepaka camp in the northwest of Erbil, during an operation to attack ISIS militants in Mosul, Iraq, Oct. 20, 2016. 

A displaced man complains about the lack of food supplies outside a processing center as smoke from a burning oil refinery blankets Qayyara, south of Mosul, Iraq on Oct. 23, 2016.

Iraqis, who fled violence in Mosul, wait to enter Syria Democratic Forces (SDF) controlled land, near the Iraqi border, in Hasaka Governorate, Oct. 23, 2016. 

Iraqi forces wear protective masks after winds brought fumes from a nearby sulfur plant set alight by ISIS militants, south of Mosul in Qayyara, Iraq, Oct. 22, 2016. 

An Iraqi special forces soldier fires a rifle during clashes with ISIS fighters in Bartella, east of Mosul, Iraq, Oct. 20, 2016. 

Smoke rises from burning oil wells on October 18, 2016 near the town of Qayyarah, south of Mosul.

Tens of thousands of Iraqi forces were making gains on ISIS in Mosul in an offensive U.S. President Barack Obama warned would be a “difficult fight.” 

A Kurdish Peshmerga fighter leans out of his military vehicle which has taken several direct hits from ISIS snipers, including those on the windscreen, Oct. 18, 2016 in the small town of Bartella near Mosul. 

Forces from countries including Britain, America and France have joined Iraq and Iraqi Kurdistan to launch what is believed to be the largest ground operation since the invasion of Iraq in 2003 to retake Mosul from the ISIS, who have held it since 2014. 

A still image taken from an ISIS video, said to be shot in Mosul on October 18 and released through the group’s Amaq news agency, shows an unidentified militant addressing the camera.

Homes destroyed by Islamic State militants, are seen on the outskirts of Bartila, east of Mosul, October 19, 2016. 

Black smoke from burning tires, used by ISIS forces to hamper the visibility of Iraqi forces, is seen in this satellite image of the city of Mosul on October 18, 2016.

Displaced Iraqis from the Bajwaniyah village, about 30 kms south of Mosul, who fled fighting in the Mosul area carry a white flag as they approach security forces on October 18, 2016

A member of Iraqi forces stands as smoke billows from the town of Qayyarah, south of Mosul, during the operation to recapture the city from the Islamic State group. Tens of thousands of Iraqi forces were making gains on the Islamic State group in Mosul in an offensive US President Barack Obama warned would be a “difficult fight”. A massive cloud of dark grey smoke blots out the horizon as the result of oil wells being set afire by IS in an effort to provide cover from air strikes, Oct. 18, 2016.  

Members of Iraqi forces drive in an armored vehicle, as they head to the frontline, on October 18, 2016 near the town of Qayyarah, south of Mosul.

A Kurdish Peshmerga soldier stands in a tunnel dug by ISIS in a village recently recaptured by the Kurds during the battle to retake Mosul, on October 18, 2016 in Bartella, near Mosul in Iraq. Joint forces from countries including Britain, U.S.A and France have joined Iraq and Iraqi Kurdistan to launch what is believed to be the largest ground operation since the invasion of Iraq in 2003 to retake Iraq’s second largest city from the Islamic State who have held it since 2014. 

A peshmerga fighter walks through the kitchen of an underground tunnel made by ISIS fighters, Tuesday, Oct. 18, 2016. 

The Kurdish forces found the tunnel in the town of Badana that was liberated from the ISIS on Monday. The fighters built tunnels under residential areas so they could move without being seen from above to avoid airstrikes.

 An Iraqi policeman inspects his weapon at the Qayyarah military base, about 60 kilometers (35 miles) south of Mosul, on Oct. 16, 2016, as forces prepare for the offensive after regaining much of the territory the jihadists seized in 2014 and 2015.

Photo: Iraqi forces gather in the area of al-Shourah, some 45 kms south of Mosul, as they advance towards the city on Oct. 17, 2016. 

Peshmerga forces sit in the back of a vehicle in the east of Mosul during an operation to attack Islamic State militants in Mosul, Iraq, October 18, 2016. 

A Peshmerga convoy drives towards a frontline in Khazer, about 30 kilometers (19 miles) east of Mosul, Iraq, Monday, Oct. 17, 2016. 

Convoys of Iraqi, Kurdish and U.S. forces moved east of Mosul along the front line early Monday as U.S.-led coalition airstrikes sent plumes of smoke into the air and heavy artillery rounds rumbled in the distance

A picture taken from the top of Mount Zardak, about 25 kilometres east of Mosul, shows smoke billowing on the outskirts of the Iraqi city of Nineveh, during an operation against Islamic State (IS) group jihadists, on October 17, 2016. Thousands of Iraq’s Kurdish peshmerga forces advanced on jihadist-held villages east of Mosul as part of a broad operation to retake the city from the Islamic State group.

Iraqi Kurdish Peshmerga fighters hold a position on the top of Mount Zardak, about 25 kilometres east of Mosul, on October 17, 2016. 

Iraqi forces deploy in the area of al-Shourah, some 20 miles south of Mosul, as they advance towards the city, Oct. 17, 2016.

ISIS seized the city more than two years ago. The unprecedented operation to retake the city is expected to take weeks, even months. 

In Washington, Defense Secretary Ash Carter called the launch of the Mosul operation “a decisive moment in the campaign” to defeat ISIS. 

The U.S. is providing airstrikes, training and logistical support, but insists Iraqis are leading the charge.

Iraqi Kurdish Peshmerga fighters fire a multiple rocket launcher from the top of Mount Zardak, about 25 kilometers east of Mosul, on Oct. 17, 2016. 

A car bomb attack is seen in the east of Mosul during clashes with Islamic State militants, Iraq, October 17, 2016. 

The main roads and fields are littered with homemade bombs and suicide car bomb attacks slowed progress.

Peshmerga forces gather in the east of Mosul on Oct. 17, 2016. 

Iraqi forces deploy in the area of al-Shourah, some 45 kms south of Mosul, as they advance on Oct. 17, 2016.

Peshmerga forces gather in the east of Mosul, Oct. 17, 2016.