Iraqi forces begun their operation to retake the Islamic State stronghold of Mosul, Prime Minister Haider al-Abadi announced.



“The time of victory has come and operations to liberate Mosul have started,” Abadi said, in an address broadcast on state television. “Today I declare the start of these victorious operations to free you from the violence and terrorism of Daesh [Islamic State, formerly ISIS/ISIL].”



An offensive to retake Iraq’s second largest city has been planned for months, since Iraqi forces and loyal government militia surrounded Mosul, in the country's north. The city fell to Islamic State (IS, formerly ISIS/ISIL) in June 2014, when the terrorists conducted their offensive on Iraq, overrunning nearly a third of the country.



Before the offensive began, dozens of ambulances were lined up at the frontline ready to ferry out casualties, as thousands of Iraqi troops moved into battle positions, The Washington Post reported.



Ahead of the offensive, the country's air force allegedly dropped leaflets warning the residents of the IS stronghold of the looming US-supported offensive. Iraqi forces have also cut off any escape routes for ISIS fighters.



A day before the offensive, the US Special Presidential Envoy for the Global Coalition to Counter ISIL, Brett McGurk, warned of the unpredictability of the Mosul battle.



"This will be a very unpredictable, very dynamic, very uncertain operation," McGurk said, NBC reported. "We do not know what Daesh is going to do in Mosul."



Just ahead of the operation, the International Committee of the Red Cross (ICRC), warned of the humanitarian catastrophe that the offense could cause, saying that the battle could create a million refugees.



Some 30,000 Iraqi and Kurdish forces are now up against an estimated 3,000 to 4,500 IS militants in Mosul, where approximately 1 million civilians are now caught in the crosshairs.



In addition to Iraqi and militia forces, it is widely believed that US troops could also participate in the offensive. Late last month, President Obama authorized the dispatch of an additional 600 American troops to Iraq to assist with the Mosul
operation. Before the announcement, the US had 4,500 troops in Iraq, years after the Obama administration officially withdrew all American troops from the country.