The military operation to wrest Mosul from the Islamic State group could potentially become the single largest, most complex humanitarian operation in the world in 2016, a U.N. official said Monday. 
 
 Speaking via video-link from Iraq, Lise Grande, the U.N. humanitarian coordinator for Iraq, said that in the worst case scenario, some 1 million civilians could flee the city with 700,000 of them requiring shelter — overwhelming emergency sites that currently only have the capacity to hold 60,000 people. 
 
 "Our capacity to support 700,000 people in the short-term — we couldn't do it. And certainly if we had to mount a response over the intermediate-term, if they couldn't go back to Mosul quickly, if there was too much damage in the city, then it would test us to the breaking point," Grande said. 
 
 She said that the U.N. was especially concerned about the safety of the estimated 1.2 to 1.5 million civilians inside Mosul who may get caught in the fighting. She said officials were also concerned that IS had already booby trapped parts of Mosul and positioned snipers within the city. 
 
 "In the worst case scenario, we can't rule out the possibility that there may be a chemical weapons attack. We also fear that ISIL, as they did in Fallujah, may try and hold civilian populations either as human shields or forcibly expel huge numbers of civilians in the face of an attack by the Iraqi security forces knowing the Iraqi forces will not fire on their own people," Grande said, using another acronym for the Islamic State group. 
 
 Grande said she has heard reports of people charging as much as $10,000 to smuggle people out of Mosul ahead of the operation to retake the city that was launched Monday. She said that, so far, the U.N. hasn't detected any population movements but that they were expected within the coming days. 
 
 Largely due to a lack of funding from the international community, the U.N. and its partners have only set up six emergency sites with a capacity to hold some 60,000 people. But Grande said in the next few weeks 22 emergency sites should be in place with a capacity to hold over 400,000 people — far short of the 700,000 people who could potentially flood out of the city. 
 
 "W, we're still short and everyone who's working on this operation knows that. We're continuing to discuss with authorities what might have to happen," Grande said. 
 
 Mosul, Iraq's second largest city, fell to IS in the summer of 2014. Weeks later the head of the extremist group, Abu Bakr al-Baghdadi, announced the formation of a self-styled caliphate in Iraq and Syria from the pulpit of a Mosul mosque. 
 
 If successful, the liberation of Mosul would be the biggest blow yet to the Islamic State group. ||||| Long-awaited offensive begins to recapture city that has been under Islamic State control 
 
 A long-awaited offensive to seize back Mosul after two years of Isis control has begun with columns of armour and military starting to move on the northern Iraqi city. 
 
 The start of the offensive, which has been months in the planning, was announced in an address on state television by Iraq’s prime minister in the early hours of Monday morning. 
 
 Battle for Mosul begins: Iraqi and Kurdish forces launch assault on Isis stronghold – latest news Read more 
 
 Haider al-Abadi said: “We have been battling Isis for more than two years. We started fighting Isis in the outskirts of Baghdad, and thank God we are now fighting them in the outskirts of Mosul, and God willing the decisive battle will be soon. 
 
 “These forces that are liberating you today, they have one goal in Mosul which is to get rid of Daesh and to secure your dignity. They are there for your sake,” he said. 
 
 After a month-long buildup, the last urban stronghold of Islamic State in Iraq has for several days been almost completely surrounded by a 30,000-strong force. 
 
 On Monday morning just before dawn, columns of Kurdish Peshmerga fighters could be seen lined up for the offensive to the north-east of the city. The forces had taken control of seven villages and the main road linking Mosul with the Iraqi Kurdish regional capital, Irbil, by 10am BST, Turkey’s state-run news agency reported. 
 
 Soldiers had earlier stood by bonfires singing battle hymns while in the distance the sound of airstrikes reverberated along with a regularly artillery barrage. 
 
 Why is the battle for Mosul significant? Mosul is Islamic State's last urban stronghold in Iraq, and the assault is the most critical challenge yet to the group's caliphate. Since Isis leader Abu Bakr al-Baghdadi declared the establishment of a caliphate from the city in June 2014, Mosul has been central to the group’s ambitions to spread its ruthless interpretation of Islamic law throughout the Arab world and beyond. Victory over Isis appears very likely, but there are concerns about what comes next: how to provide for up to 1.3 million refugees and how to re-establish governance in a city brutalised by tyranny. 
 
 South of the city, Iraqi forces, which had driven hundreds of miles for what Baghdad has hailed as a last battle against the terrorist group, moved into their final positions on Friday. 
 
 Also on the ground are US, British and French special forces, which have been advising the peshmerga and will play a prominent role in calling in airstrikes against Isis targets inside the city. 
 
 
 
 Skirmishes have flared outside Iraqi’s second largest city over the last few days with an airstrike on one of its main bridges on Sunday. It is not clear who was responsible for the strike on the al-Hurriya bridge but Amaq, the news agency associated with Isis, blamed US forces. It is thought that the destruction of the bridge could hinder Isis fighters trying to flee the city. 
 
 
 
 Early on Monday, a dense, noxious haze hung over the mountains and the plains leading to Mosul – a haze caused by oil fires lit by Isis in anticipation of the attack. 
 
 Pehmerga forces are aiming to take three villages and advance up to 12km on the first day of the offensive but insist they will not enter Mosul itself. Isis is believed to have heavily mined the roads leading into its territory with large numbers of improvised devices and the Iraqi government has previously warned Mosul resident to stay in their homes. 
 
 Ahead of Abadi’s televised statement, thousands of four-page leaflets were dropped across the city telling civilians to avoid certain parts of the city and declaring it was “victory time”. 
 
 
 
 Ahmed al-Assadi, a lawmaker and spokesman for the militias, said: “We promise you that it will be a great victory fitting with the greatness of Iraq and its history and its people.” 
 
 The fight is expected to last weeks, if not months, and if the battles to wrest Falluja and Ramadi from the grip of Isis are any indication, Mosul is predicted to be a protracted and difficult affair. 
 
 The assault on the city is the most critical challenge yet to Isis’s two-year-old caliphate, which has shredded state authority in the region’s heartland, caused a mass exodus of refugees, attempted a genocide of minorities and led to grave doubts over the future of the country. 
 
 Isis is thought to have about 6,000 fighters ready to defend Mosul, hidden among an estimated civilian population of approximately 600,000, most of whom are expected to flee as the battle intensifies. Before its occupation by Isis, the city was home to more than 2 million people. 
 
 Five key questions about the battle for Mosul Read more 
 
 The International Committee of the Red Cross has warned that the battle for the city could result in a humanitarian crisis with up to a million refugees fleeing. 
 
 Militants have banned civilians from leaving the city, set up checkpoints on outwards roads and blown up the homes of those who fled. 
 
 
 
 While leaving can mean trekking through minefields and the risk of discovery and punishment by Isis, those who stay know they face airstrikes, street battles, a potential siege by the Iraqi security forces and the grim possibility of being used as human shields by Isis. 
 
 The US has recently deployed an additional 600 troops to aid in the city’s capture, bringing the total number of US personnel to more than 5,200, according to the Pentagon. 
 
 
 
 Victory over Isis will not solve Iraq’s problems | Ranj Alaaldin Read more 
 
 Jeff Davis, a Pentagon spokesman, said: “This is the last big holdout in Iraq for Isil.” 
 
 
 
 The US said on Sunday night that it was proud to stand with its allies in the offensive to retake Mosul. In a statement, the defence secretary, Ash Carter, said: “This is a decisive moment in the campaign to deliver Isil a lasting defeat. 
 
 “The United States and the rest of the international coalition stand ready to support Iraqi security forces, Peshmerga fighters and the people of Iraq in the difficult fight ahead. We are confident our Iraqi partners will prevail against our common enemy and free Mosul and the rest of Iraq from Isil’s hatred and brutality.” 
 
 If the Mosul offensive is a success, what could this mean for Isis? Read more 
 
 Brett McGurk, the US envoy to the coalition against Islamic State, said in a message on Twitter. “Godspeed to the heroic Iraqi forces, Kurdish peshmerga, and Ninewa volunteers. We are proud to stand with you in this historic operation.” 
 
 
 
 The UN deputy secretary general for humanitarian affairs and emergency relief voiced grave concern about the risks faced by civilians. 
 
 “I am extremely concerned for the safety of up to 1.5 million people living in Mosul who may be impacted by military operations to retake the city from Isil,” Stephen O’Brien said. 
 
 He warned that families were at extreme risk of being caught in crossfire or targeted by snipers.
– The military operation to wrest Mosul from ISIS could become the single largest, most complex humanitarian operation in the world in 2016, a UN official said Monday. Lise Grande, the UN humanitarian coordinator for Iraq, said that in the worst case scenario, some 1 million civilians could flee the city, with 700,000 of them requiring shelter—overwhelming emergency sites that currently only have the capacity to hold 60,000 people, the AP reports. It can't be done right now, and even in "the intermediate-term, if they couldn't go back to Mosul quickly, if there was too much damage in the city, then it would test us to the breaking point," Grande said. "In the worst-case scenario, we can't rule out the possibility that there may be a chemical weapons attack," Grande said, warning that ISIS "may try and hold civilian populations either as human shields or forcibly expel huge numbers of civilians in the face of an attack by the Iraqi security forces knowing the Iraqi forces will not fire on their own people." The Guardian reports that American aircraft have started dropping millions of leaflets over Mosul, warning residents to stay in their homes, advising them on how to comfort children and avoid flying glass during bombings—and advising against trying to flee the city.