U.S.-backed Iraqi forces on Sunday launched a ground offensive to dislodge Islamic State (ISIS) militants from their remaining stronghold in Mosul, in the western part of the city, and put an end to their ambitions for territorial rule in Iraq.
Iraqi Prime Minister Haider al-Abadi announced the start of the offensive, asking Iraqi forces to "respect human rights" during the battle and to take care of those displaced by the fighting.
ISIS militants are essentially under siege in western Mosul, along with an estimated 650,000 civilians, after they were forced out of the eastern part of the city in the first phase of an offensive that concluded last month, after 100 days of fighting.
Up to 400,000 civilians could be displaced by the offensive as residents of western Mosul suffer food and fuel shortages and markets are closed, United Nations Humanitarian Coordinator for Iraq Lise Grande told Reuters on Saturday.
Iraqi federal police units are leading a northward charge on the Mosul districts that lie west of the Tigris river, aiming to capture Mosul airport, just south of the city, according to statements from the armed forces joint command. They captured several villages and a local power distribution station in the first hours and killed several militants including snipers, the statements said.
Smoke rises after members of the Iraqi rapid response forces fired a missile toward Islamic State militants during a battle in the south of Mosul, Iraq February 19. Zohra Bensemra/Reuters
The police are advancing up the Tigris river valley toward the airport, whilst the Rapid Response, an elite Interior Ministry unit, cut across more open terrain to the southwest.
"Mosul would be a tough fight for any army in the world," the commander of the U.S.-led coalition forces, Lt. Gen. Stephen Townsend, said in a statement.
ISIS has escalated its insurgency in retaliation for the military setbacks that have, over the past year, forced it out of most Iraqi cities it had captured in 2014 and 2015.
Two militants blew themselves up in eastern Mosul on Sunday, killing three soldiers and two civilians, and wounding a dozen people, security sources said.
Iraqi planes dropped millions of leaflets on western Mosul warning residents that the battle to dislodge ISIS was imminent, the Iraqi Defence Ministry said on Saturday. The leaflets told the jihadists to surrender "or face a fatal end."
Commanders expect the battle to be more difficult than in the east because tanks and armored vehicles cannot pass through its narrow alleyways.
The militants have developed a network of passageways and tunnels to enable them to hide and fight among civilians, disappear after hit-and-run operations and track government troop movements, according to residents.
Western Mosul contains the old city center, with its ancient souks, Grand Mosque and most government administrative buildings.
It was from the pulpit of the Mosul Grand Mosque that ISIS leader Abu Bakr al-Baghdadi declared a self-styled "caliphate" over parts of Syria and Iraq in 2014. The city, Iraq's second biggest, is the largest urban center captured by Islamic State in both countries and its de facto capital in Iraq. Raqqa is its capital in Syria.
ISIS was thought to have up to 6,000 fighters in Mosul when the government's offensive started in mid-October. Of those, more than 1,000 have been killed, according to Iraqi estimates.
The remainder now face a 100,000-strong force made up of Iraqi armed forces, including elite paratroopers and police, Kurdish forces and Iranian-trained Shi'ite paramilitary groups.
The westward road that links the city to Syria was cut in November by the Shi'ite paramilitary known as Popular Mobilisation. The militants are in charge of the road that links Mosul to Tal Afar, a town they control 60 km (40 miles) to the west.
Coalition aircraft and artillery have continued to bombard targets in the west during the break that followed the taking of eastern Mosul.
The United States, which has deployed more than 5,000 troops in the fighting, leads an international coalition providing air and ground support, including artillery fire, to the Iraqi and Kurdish forces.
Capturing Mosul would effectively end the Sunni group's ambitions for territorial rule in Iraq. The militants are expected to continue to wage an insurgency, however, carrying out suicide bombings and inspiring lone-wolf actions abroad.Try Newsweek: Subscription offers