Image copyright Reuters Image caption Iraqi forces bombarded IS positions ahead of the advance

Iraqi government forces have seized several villages as they move towards an assault on the last area held by the so-called Islamic State (IS) in Mosul.

Hundreds of military vehicles, backed by air power, rolled across the desert towards IS positions early on Sunday.

The progress on Sunday in the south of the city, the second biggest in Iraq, takes them within striking distance of Mosul airport.

Fears have been voiced about the safety of many thousands of trapped civilians.

The offensive was formally announced by Iraqi Prime Minister Haider al-Abadi early on Sunday.

Army Staff Lieutenant General Abdulamir Yarallah said in a statement that elite Rapid Response units captured the villages of Athbah and Al-Lazzagah - two villages south of Mosul airport.

Attack on west Mosul: Day one in pictures

Government forces retook the eastern side of the city, the last major IS stronghold in Iraq, last month. But military officials say the western side, with its narrow, winding streets, may prove a bigger challenge.

For now, there is no advance from eastern Mosul as all bridges from there to the west of the city, across the Tigris river, have been destroyed.

Lieutenant General Stephen Townsend, the commander of the US-led coalition forces, said in a statement on Sunday: "Mosul would be a tough fight for any army in the world."

Special forces units safely detonated a number of IS car bombs as they cleared villages south of Mosul, according to the BBC's Quentin Sommerville, who is embedded with the troops.

As well as primed car bombs, the jihadists left behind SIM cards, clothes, instant coffee and weapons as they retreated.

Image copyright Quentin Sommerville/BBC Image caption A hidden and still live car bomb found in a village home

The UN has voiced concern about civilians trapped there, amid reports that they could number up to 650,000. Leaflets warning residents of an imminent offensive were earlier dropped over the west of the city.

Charity Save the Children said on Sunday it believed that as many as 350,000 children were trapped.

"This is the grim choice for children in western Mosul right now: bombs, crossfire and hunger if they stay; or execution and snipers if they try to run," said the charity's Iraq country director, Maurizio Crivallero.

The BBC's Quentin Sommerville is embedded with the Emergency Response Division special forces troops near Mosul

Media playback is unsupported on your device Media caption Quentin Sommerville: "Coalition aircraft have been softening up IS positions"

The assault began just after dawn, after days of coalition air strikes, with hundreds of armoured vehicles, thousands of men, and support from helicopter gunships.

The men of Iraq's Emergency Response Division, police special forces are leading the attack. Their targets are three IS held villages to the south of west Mosul. They are trying to gain the high ground from IS, which will give them sight of the city's airport and its southern edge.

The government forces made quick gains but have been slowed as they begin to take villages. There are no signs of any civilians. Heavy machine gunfire, rockets and artillery fire are constant.

For the first time in nearly three years, the Iraqi flag is again flying over the south of western Mosul.

Image copyright Quentin Sommerville/BBC Image caption Soldiers rest during the offensive in southern Mosul

Image copyright Quentin Sommerville/BBC Image caption A soldier looks out over the desert as the offensive begins

Follow Quentin Sommerville on Twitter

Iraqi forces have now all but surrounded the western part of Mosul, while the US-led coalition has been carrying out air strikes on IS targets.

Ahead of the launch of the operation, Mr Abadi said in a televised speech: "We announce the start of a new phase in the operation, we are coming to Nineveh to liberate the western side of Mosul."

"Our forces are beginning the liberation of the citizens from the terror of Daesh [IS]," he added, quoted by AFP news agency.

The UN humanitarian co-ordinator for Iraq, Lise Grande, has urged all parties involved to "do absolutely everything they can to ensure that civilians survive the battle, and that they live".

"Absolutely nothing is more important going into the campaign to retake western Mosul," she told the BBC on Saturday.

As the advance got under way, the UN commissioner for human rights called on the Iraqi government to investigate videos shared on social media that appeared to show Iraqi troops brutally abusing and executing IS fighters on the streets of east Mosul late last year.

The videos have not been verified at this stage by any government authority or independent group. The Iraqi prime minister's office said it had launched an investigation.

Media playback is unsupported on your device Media caption Music blares as Iraqi forces push across the desert

The offensive on the eastern part of the city was launched on 17 October, more than two years after jihadists overran Mosul before seizing control of much of northern and western Iraq.

Experts warn that western Mosul, although slightly smaller than the east, is more densely populated and includes districts that are seen as pro-IS.

The UN said in late January that almost half of all the casualties in Mosul were civilians. At least 1,096 have been killed and 694 injured across Nineveh province since the start of October.</s>According to the UN Office for Coordination of Humanitarian Affairs (OCHA) in the country, food and fuel supplies are dwindling, markets and shops have closed, running water is scarce and electricity in many neighborhoods is either intermittent or cut off.

"The situation is distressing. People, right now, are in trouble. We are hearing reports of parents struggling to feed their children and to heat their homes,?" said Lise Grande, the Humanitarian Coordinator for Iraq.

According to estimates, between 750,000 and 800,000 civilians reside in the western section of Mosul.

However, few if any commercial supplies have reached the city in the past three months since the main road to Syria was cut-off.

Sources in the city also reported that nearly half of all food shops have closed and bakeries throughout the area have run out of fuel and many can no longer afford to purchase costly flour.

RELATED: UN fears new wave of displacement as fighting escalates in Mosul and Hawiga

Prices of fuel such as kerosene and cooking gas have skyrocketed and many of the most destitute families are burning wood, furniture, plastic or garbage for cooking and heating.

Families, children face critical shortage of drinking water, do not have enough to eat

According to the UN Children's Fund (UNICEF) and the UN World Food Programme (WFP) there are critical shortages of food and safe drinking water.

Three out of five people now depend on untreated waterUNICEF Representative in Iraq Peter Hawkins

"Three out of five people now depend on untreated water from wells for cooking and drinking as water systems and treatment plants have been damaged by fighting or run out of chlorine," said Peter Hawkins, the UNICEF Representative in Iraq.

"Food prices in western Mosul are almost double than in eastern Mosul," added Sally Haydock, the WFP Representative in the country, noting that many families do not have enough to eat.

Preparing to aid as many as 400,000 fleeing civilians

A UNICEF-supported water truck and trash collection programme at a camp in Al Qayyarah, Ninewa Governorate, Iraq. More than 6,000 people displaced from Mosul are residing at this camp. (file) Photo: OCHA / Philippe Kropf

According to OCHA, UN and humanitarian partners are rushing to prepare for the humanitarian impact of the military operation.

"We don't know what will happen during the military campaign but we have to be ready for all scenarios. Tens of thousands of people may flee or be forced to leave the city. Hundreds of thousands of civilians might be trapped — maybe for weeks, maybe for months,?" said Ms. Grande.

Emergency sites are being constructed south of the city and stocks of life-saving supplies are being pre-positioned for the 250,000-400,000 civilians who may flee.

"Protecting civilians is the highest priority in a situation like this — nothing is more important [...] The battle hasn't started but already there is a humanitarian crisis,?" the UN humanitarian official added.</s>Story highlights Iraqi forces claim 79 ISIS militants killed on first day of operation

Mosul's west bank has been one of the Iraqi force's toughest challenges

(CNN) Iraq has launched an operation to regain control of western Mosul from ISIS militants, Prime Minister Haider al-Abadi said Sunday.

The operation comes weeks after Iraqi forces recaptured eastern Mosul across the Tigris River. On the first day of the new offensive, Iraqi Federal Police forces said they killed 79 ISIS militants, destroyed weapons facilities and regained control of 10 villages.

The prime minister described the operation as a "new dawn" in the liberation of Mosul, ISIS' last major stronghold in the country.

"Go forward with my blessing, heroic forces of Iraq," he said on state television.

Fighters of the Popular Mobilisation paramilitaries prepare defensive positions near the frontline village of Ayn al-Hisan, on the outskirts of Tal Afar, west of Mosul, on Saturday.

Fears of 'deadly and indiscriminate' deaths

Read More</s>The Iraqi Prime Minister Haider al-Abadi on Sunday, (19 February) announced the launch of a ground offensive in western Mosul to drive the Islamic State (Isis) out of the area.

"We announce the start of a new phase in the operation, we are coming to Nineveh to liberate the western side of Mosul. Our forces are beginning the liberation of the citizens from the terror of Daesh [IS]," he added.

The Iraqi air force has reportedly dropped leaflets on western Mosul warning its residents of an impending ground offensive to oust the IS (Daesh) from the area, the Iraqi defence ministry said in a statement, Reuters reported.

The statement said the leaflets "contain instructions for the citizens to get ready to welcome the Iraqi forces that are coming to liberate their areas and to warn the Daesh (Islamic State) members to lay down their weapons and surrender".

At least 650,000 civilians in western Mosul are under siege along with the Isis militants. The US backed Iraqi forces were successful in ousting the terrorist group from the eastern part of Mosul in a battle that came to an end in January and now have all but surrounded the western side.

Meanwhile, the United Nations has warned that the safety of the thousands of civilians trapped in the area is a top priority.

Lise Grande, the UN humanitarian co-ordinator for Iraq told the BBC that it had made the safety of civilians its top priority when the Iraqi forces waged an offensive to take back eastern Mosul.

She added that the Iraqi forces "need to ensure that that humanitarian concept of operations is adhered to, and that all of the parties to the conflict do absolutely everything they can to ensure that civilians survive the battle, and that they live."

"Absolutely nothing is more important going into the campaign to retake western Mosul," Grande said.

According to reports, retaking western Mosul could prove to be a bigger challenge due to its narrow streets.</s>HAMAM AL-ALIL, Iraq -- U.S.-backed Iraqi forces launched an air-and-ground offensive Sunday to retake western Mosul from Islamic State militants and drive the extremist group from its last major urban bastion in Iraq.

"It's a new dawn, a dawn of victories," Iraqi Prime Minister Haider al-Abadi said in an address on state television early Sunday, as Iraqi forces, including units from the army, federal police and state-sanctioned militias, advanced on Mosul from the south and west.

The operation aims to reverse the Islamic State's occupation of cities and towns across Iraq since the summer of 2014, a defeat for al-Abadi's predecessor, former Prime Minister Nouri al-Maliki, and a setback that raised doubts about the morale and capabilities of Iraq's military. The latest advance on Mosul comes at a time of rising tension between the Iraqi government and its principal military partner, the United States, over President Donald Trump's administration's decision to halt immigration from seven Muslim-majority countries, including Iraq.

It is also taking place amid new concerns about the condition of hundreds of thousands of civilians still trapped in the western part of the city. Food, water and cooking fuel have all been reported in short supply, and residents have described increased harassment from Islamic State fighters preparing for the attack.

Overnight, planes covered the ground with leaflets, directly appealing to the group's fighters to surrender.

"To those of you who were intrigued by the ISIS ideology," one of the leaflets said, using an acronym for the Islamic State, "this is your last opportunity to quit your work with ISIS and to leave those foreigners who are in your homeland. Stay at home, raising the white flags as the forces approach."

The operation that began Sunday crossed the Tigris River, which bisects Mosul, to move into its western district, where Iraqi commanders expect an even tougher fight, with close-quarters urban combat in narrow streets, through neighborhoods densely packed with civilians.

Ground units pushed into a belt of villages outside the country's second-largest city, and plumes of smoke rose into the sky early in the morning as U.S.-led coalition jets struck militant positions southwest of Mosul and militarized Iraqi police fired artillery.

"This is zero hour and we are going to end this war, God willing," said Mahmoud Mansour, a police officer, as he prepared to move out.

Throughout the night, a steady barrage targeted Islamic State positions just north of the village of Areyj, about 7 miles outside of Mosul.

The operation comes after an overall push to free Mosul that began in October, with local troops pushing from the east into the city's geographically larger but more sparsely populated eastern half. In late January, they reached the banks of the Tigris River and declared the city's eastern section liberated, but the militants continued to stage attacks there, including two suicide bombings against government forces on Sunday.

Because all five of the bridges spanning the Tigris have been bombed, for this operation Iraqi troops traced a circuitous path to western Mosul, initially approaching it from the city's south.

Police units quickly entered the village of Athba, about 3 miles southwest of Mosul's international airport, encountering only light resistance. Separately, the Iraqi Army's 9th Division moved into the village of Bakhira, also southwest of the city, the Ministry of Defense said.

The U.S.-led coalition has been providing close air support throughout the 4-month-old Mosul offensive and carried out nine airstrikes against the Islamic State near Mosul on Saturday, Central Command said. U.S. special operations forces are embedded with some Iraqi units, and thousands of American soldiers are in Iraq to provide logistical and other support.

Despite the sight of U.S. special forces near the front lines, Defense Secretary James N. Mattis said Sunday during a visit to Arab allies in Abu Dhabi there has been no change to rules of engagement regarding U.S. forces' role in the Mosul operation since President Donald Trump took office.

"We are very close to it, if not already engaged in that fight," Mattis told reporters in Abu Dhabi.

He said the U.S.-backed coalition fighting the Islamic State would "continue with the accelerated effort to destroy" the group.

"The isolation phase has been going on for some time now," Mattis said. "The attack into the city is something I don't want to get into details about because I owe confidentiality to the troops who are actually making the attack."

He plans to present the White House with a more aggressive plan to combat Islamic State by month's end, but acknowledged that U.S. airstrikes have pounded Islamic State targets in western Mosul from the air in the days ahead of the Iraqi assault, hitting militant command and control facilities.

Citing witnesses in western Mosul, the United Nations said nearly half of all food shops were closed and bakeries had shut down for lack of fuel and an inability to purchase costly flour. Prices of kerosene and cooking gas have skyrocketed, and many of the most destitute families are burning wood, furniture, plastic or garbage for cooking and heating.

The U.N. also said hundreds of thousands of civilians trapped inside their homes in Mosul "are at extreme risk," with dwindling fuel, food and water and scarce electricity.

"The situation is distressing. People, right now, are in trouble," Lise Grande, the U.N. humanitarian coordinator for Iraq, said in a statement. "We are hearing reports of parents struggling to feed their children and to heat their homes."

Peter Hawkins, of the U.N. agency for children, said: "Three out of five people now depend on untreated water from wells for cooking and drinking as water systems and treatment plants have been damaged by fighting or run out of chlorine."

The humanitarian agencies were gearing up to aid 250,000 to 400,000 civilians who may flee because of the fighting, the statement said. The U.N. estimates that 750,000 civilians may be left in western Mosul.

An advance the Islamic State has made is improving its mastery of the use of small drones, which are available off-the-shelf in malls across the region, including in Irbil, the nearest major city to Mosul. They use the drones to pinpoint army positions and to target them, and recently recovered Islamic State documents show how the group has cobbled together its own drone program. Iraqi forces describe how they frequently see the 2- to 4-foot-long aircraft overhead, whining like a lawn mower. Then 30 minutes later, they will take incoming fire at that location.

Lt. Gen. Stephen Townsend, a top U.S. commander in Iraq, said the Iraqi forces are an "increasingly capable, formidable and professional force."

"Mosul would be a tough fight for any army in the world, and the Iraqi forces have risen to the challenge," he said in a statement.

Brig. Gen. Yahya Rasool, an Iraqi military spokesman, said a suicide bomber struck a patrol of government-allied Sunni tribal fighters in the Zihoor neighborhood, while another targeted Iraqi troops in Nabi Younis. The Islamic State claimed responsibility for both attacks.

Rasool declined to provide casualty figures. Two policemen said one Sunni fighter was killed and nine were wounded in the first attack, while the second attack wounded five soldiers. They spoke on condition of anonymity because they were not authorized to release information.

Iraqi special operations forces, regular army and federal police units are taking part in the offensive along with government-approved paramilitary forces, mainly consisting of Shiite militias, which are operating on the city's outskirts.

Information for this article was contributed by Bram Janssen, Sinan Salaheddin, Qassim Abdul-Zahra, Maamoun Youssef and Joseph Krauss of The Associated Press, by Nabih Bulos And W.J. Hennigan of Tribune News Service, and by Rukmini Callimachi and Falih Hassan of The New York Times.</s>US-backed Iraqi forces began moving on Sunday towards Mosul’s airport, the first target of a ground offensive to capture the western side of the city that remains under control of Islamic State, the Iraqi military said.

Iraqi prime minister Haider al-Abadi earlier on Sunday announced the formal start of a ground offensive on western Mosul, asking the Iraqi forces to “respect human rights’’ during the battle.

Islamic State militants are essentially under siege in western Mosul, along with an estimated 650,000 civilians, after US-backed forces surrounding the city forced them from the east in the first phase of an offensive that concluded last month. Iraqi federal police units are leading a northward charge on the Mosul districts that lie west of the Tigris river, aiming to capture the Mosul airport, located 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 of their progress and killed several militants including snipers, the statements said.

“Mosul would be a tough fight for any army in the world,” the commander of the US-led coalitions forces, Lt. Gen. Stephen Townsend, said in a statement.

Iraqi planes dropped millions of leaflets on the western side of Mosul warning residents that the battle to dislodge Islamic State was imminent as troops began moving in their direction, the Iraqi Defence Ministry said on Saturday.

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.

Commanders expect the battle in the west to be more difficult than in the east because tanks and armoured vehicles cannot pass through its narrow streets and alleyways.

The militants have also developed a network of passageways and tunnels that will enable them to hide and fight among the civilians, disappear after hit-and-run operations and track government troop movements, according to residents.

Western Mosul contains the old city centre, with its ancient souks, Grand Mosque and most government administrative buildings.

It was from the pulpit of the Mosul Grand Mosque that Islamic State leader Abu Bakr al-Baghdadi declared a “caliphate” over parts of Syria and Iraq in 2014.

The city - Iraq’s second biggest - is the largest urban centre captured by Islamic State in both countries and its de facto capital in Iraq. Raqqa is its capital in Syria. Islamic State was thought to have up to 6,000 fighters in Mosul when the government’s offensive started in mid-October. Of those, more than one thousand 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 Shia paramilitary groups.

The United States, which has deployed more than 5,000 troops in the fighting, leads an international coalition providing critical air and ground support, including artillery fire, to the Iraqi and Kurdish forces.

The Sunni group imposed a radical version of Islam in Mosul, banning cigarettes, televisions and radios, and forcing men to grow beards and women to cover from head to toe. Citizens who failed to comply risked death.

Capturing Mosul would effectively end the militants’ ambitions for territorial rule in Iraq. They are expected to continue to wage an insurgency, however, carrying out suicide bombings and inspiring lone-wolf actions abroad.</s>U.S.-backed Iraqi forces launched a large-scale military operation on Sunday to dislodge Islamic State militants from the western half of Mosul, the latest phase in a four-month-old offensive to retake Iraq's second largest city.The battle for western Mosul promises to be the most daunting yet, as the half of the city west of the Tigris River has older, narrower streets and is still home to hundreds of thousands of civilians, who have been told to shelter in place.Iraq declared eastern Mosul "fully liberated" last month, but IS has continued to launch attacks there. Hours after the latest operation was announced, suicide bombers struck troops and pro-government Sunni militiamen in eastern Mosul.Prime Minister Haider al-Abadi announced the start of the operation on state TV, saying government forces were moving to "liberate the people of Mosul from Daesh oppression and terrorism forever," using the Arabic acronym for IS. He called on security forces to deal with civilians properly and to respect human rights.Plumes of smoke were seen rising into the sky early Sunday morning as U.S.-led coalition jets struck militant positions southwest of Mosul and militarized Iraqi police fired artillery toward the city. Heavily armed police units were getting ready to move north with their armored vehicles from a base just southwest of the city."This is zero hour and we are going to end this war, God willing," said Mahmoud Mansour, a police officer, as he prepared to move out.The immediate objective was to take the villages on the southern outskirts of Mosul airport, a police spokesman told The Associated Press. The officer spoke on condition of anonymity because he was not authorized to brief reporters.Police units quickly moved into the village of Athba, about 3 miles (5 kilometers) southwest of the airport, encountering only light resistance, according to an AP reporter traveling with them. Separately, the army's 9th Division moved into the village of Bakhira, also southwest of the city, the Iraqi Ministry of Defense said.The United Nations meanwhile warned that hundreds of thousands of civilians trapped inside their houses "are at extreme risk," with dwindling fuel and food supplies and scare drinking water and electricity."The situation is distressing. People, right now, are in trouble," Lise Grande, the U.N. humanitarian coordinator for Iraq, said in a statement. "We are hearing reports of parents struggling to feed their children and to heat their homes," Grande said.Citing witnesses in western Mosul, the U.N. said nearly half of all food shops were closed and bakeries had shut down due to a lack of fuel and an inability to purchase costly flour. Prices of kerosene and cooking gas have skyrocketed, and many of the most destitute families are burning wood, furniture, plastic or garbage for cooking and heating."Three out of five people now depend on untreated water from wells for cooking and drinking as water systems and treatment plants have been damaged by fighting or run out of chlorine," said Peter Hawkins, of the U.N. agency for children.The humanitarian agencies were gearing up to aid 250,000 to 400,000 civilians who may flee due to fighting, the statement said. The U.N. estimates that about 750,000 civilians may be left in western Mosul.Lt. Gen. Stephen Townsend, a top U.S. commander in Iraq, said the Iraqi forces are an "increasingly capable, formidable, and professional force.""Mosul would be a tough fight for any army in the world, and the Iraqi forces have risen to the challenge," he said in a statement. "They have taken the fight to the enemy and sacrificed their blood for the people of Iraq and the rest of the world."Iraqi forces spent three months driving IS from eastern Mosul, but the militants appear to have left sleeper cells to carry out attacks behind the front lines.Brig. Gen. Yahya Rasool, an Iraqi military spokesman, said a suicide bomber set off struck a patrol of Sunni tribal fighters in Zihoor neighborhood, while another targeted Iraqi troops in Nabi Younis.Rasool declined to provide casualty figures. Two policemen said one Sunni fighter was killed and nine wounded in the first attack, while the second attack wounded five soldiers. They spoke on condition of anonymity as they were not authorized to release information.Iraqi special operations forces, regular army and federal police units are taking part in the offensive along with government-approved paramilitary forces, mainly consisting of Shiite militias, which are operating on the city's outskirts.Mosul fell to IS in the summer of 2014, along with large swaths of northern and western Iraq. It is the extremist group's last major urban bastion in Iraq.</s>By Mustafa Salim, Kareem Fahim and Dan Lamothe, The Washington Post

IRBIL, Iraq – Iraqi forces resumed their offensive against the Islamic State in Mosul on Sunday after a weeks-long pause, aiming to capture the militant-controlled western half of the city, where the tight, impassable streets and teeming neighborhoods will pose a formidable challenge to the advancing fighters.

Prime Minister Haider al-Abadi announced the offensive in a televised address early Sunday, calling it “a dawn of victories.” As he spoke, units from Iraq’s army, federal police and state-sanctioned militias approached Mosul from the south and west. By day’s end, they had captured a dozen tiny and mostly vacant villages south of Mosul, along with an electricity station, officials said.

The painless start belied a complicated and arduous battle ahead. Eastern Mosul was captured in January after months of punishing urban combat that left hundreds of civilians dead and elite Iraqi units battered by the stiff militant defenses, including roadside bombs, sniper fire and explosives-laden vehicles.

Iraqi troops will face all that and worse in western Mosul, across the bombed-out bridges on the Tigris River, fighting in a warren of streets too narrow for tanks against Islamist militants who have had months to prepare a deadly welcome. Each passing week of combat poses growing risks to hundreds of thousands of civilians still in the city, facing shortages of food, water, electricity and medicine and all but sequestered in their homes until Iraqi troops arrive.

“Families in western Mosul tell us escape is not an option – if they try to flee, they risk summary execution by ISIS fighters or a gauntlet of sniper fire and land mines,” Maurizio Crivallero, the Iraq country director for Save the Children, the Britain-based charity, said in a statement last week, using an acronym for the Islamic State.

An estimated 350,000 children remain trapped in the city, he said. “The impact of artillery and other explosive weaponry in those narrow, densely-populated streets is likely to be more deadly and indiscriminate than anything we have seen in the conflict so far,” he said.

U.S. troops involved in the air campaign said Sunday that there is broad recognition that it will be harder to carry out airstrikes in the western part of the city, citing the way remaining fighters have entrenched themselves as well as the closely settled nature of neighborhoods.

“It’s going to be a full-on cat-and-mouse fight in western Mosul,” said Air Force Lt. Col. August Pfluger, a squadron commander and F-22 Raptor pilot. “We are literally fighting city block by city block, and putting ordnance where the Iraqi ground forces want them.”

The offensive aims to reverse the Islamic State’s stunning advance into cities and towns across Iraq in the summer of 2014, a humiliating defeat for Nouri al-Maliki, Abadi’s predecessor as premier, and a setback that raised concerns about the morale and capabilities of Iraq’s military.

The latest advance on Mosul also comes at a time of rising tension between the Iraqi government and the United States over the White House decision to halt immigration from seven Muslim-majority countries, including Iraq.

The Trump administration’s escalating condemnations of Iran, a dominant power in Iraq and a sponsor of Shiite militias fighting alongside Iraqi government units, has also threatened to complicate the efforts against the Islamic State.

Defense Secretary Jim Mattis, speaking Sunday in Abu Dhabi, United Arab Emirates, said that U.S. forces would continue “with the accelerated effort to destroy ISIS.”

Before the military push Sunday, thousands of leaflets were dropped over western Mosul, announcing the impending offensive and asking residents to “receive your brothers in the armed forces and cooperate with them.”

In the past few days, the United States has also stepped up its air sorties over Mosul, to about 30 to 50 a day from about 12 to 20, said Col. Kevin M. Eastland, vice commander of the Air Force’s 380th Air Expeditionary Wing. The unit has gone from using two of the six F-22s it has in the Middle East per day to four – a pace commanders do not consider sustainable for long periods because of maintenance requirements.

An F-22 pilot who asked that his name not be published because of security concerns, said some of his recent airstrikes hit a police station used by the Islamic State in Mosul and a command-and-control center. He and his colleagues had been in somewhat of a “lull,” in which they would often return to base hours later with some of their bombs, he said, but had received a list a few days ago that included about 110 “deliberate” targets that were planned for weeks by U.S. military and intelligence officials.

On the ground, the first military objectives include an Islamic State-controlled village and Mosul’s airport, both in the south of the city, Iraqi commanders said. On Sunday, in a reminder of the Islamic State’s continued ability to strike behind Iraqi lines, at least two suicide bombers carried out attacks in eastern Mosul, killing at least one person, officials said.

Fahim reported from Istanbul and Lamothe from Abu Dhabi.</s>HAMAM AL-ALIL, Iraq -- U.S.-backed Iraqi forces launched a large-scale military operation on Sunday to dislodge Islamic State militants from the western half of Mosul city, a battle that is expected to be prolonged and difficult due to a densely packed civilian population and older, narrower streets.

In a briefed televised speech on state TV, Iraqi Prime Minister Haider al-Abadi announced the start of the operation, saying the government forces were moving to "liberate the people of Mosul from Daesh oppression and terrorism forever", using the Arabic acronym for IS.

Al-Abadi called on security forces to deal with civilians properly and respect human rights.

Plumes of smoke were seen rising into the sky early Sunday morning as U.S.-led coalition jets struck militant positions southwest of Mosul and militarized police fired artillery toward the city. Heavily armed police units were getting ready to move north with their armoured vehicles from a base just southwest of the city.

"This is zero hour and we are going to end this war, God willing," said Mahmoud Mansour, a police officer, as he prepared to move out.

The immediate objective of the operation was to take the villages on the southern outskirts of Mosul airport, a police spokesman told The Associated Press. The officer spoke on condition of anonymity in line with standard procedures.

Police units quickly moved into the village of Athba about three miles southwest of the city's airport, encountering only light resistance, according to an AP reporter on the scene. Separately, the army's 9th armoured division moved into the village of Bakhira, also southwest of the city, the Iraqi Ministry of Defence said.

Shortly after the announcement, the United Nations warned that hundreds of thousands of civilians trapped inside their houses "are at extreme risk" with dwindling fuel and food supplies and scare drinking water and electricity.

"The situation is distressing. People, right now, are in trouble," Lise Grande, Humanitarian Coordinator for Iraq, said in a statement. "We are hearing reports of parents struggling to feed their children and to heat their homes," Grande said.

Citing informants from inside the western side, the U.N. said nearly half of all food shops were closed and bakeries had shut down due to a lack of fuel and an inability to purchase costly flour. Prices of kerosene and cooking gas have skyrocketed and many of the most destitute families are burning wood, furniture, plastic or garbage for cooking and heating.

"Children and their families are starting to face critical shortages of safe drinking water," Peter Hawkins, UNICEF Representative in Iraq, was quoted as saying in the statement. "Three out of five people now depend on untreated water from wells for cooking and drinking as water systems and treatment plants have been damaged by fighting or run out of chlorine."

The humanitarian agencies were gearing up to aid 250,000 to 400,000 civilians who may flee due to fighting, the statement said. The U.N. estimates that about 750,000 civilians may be left in western Mosul.

The Commander of Combined Joint Task Force Operation Inherent Resolve, Lt. Gen. Stephen Townsend, hailed the Iraqi forces in a statement as an "increasingly capable, formidable, and professional force."

"Mosul would be a tough fight for any army in the world, and the Iraqi forces have risen to the challenge," said Townsend. "They have taken the fight to the enemy and sacrificed their blood for the people of Iraq and the rest of the world."

Eastern Mosul was retaken from IS by Iraqi forces last month after a three-month battle, but the west of the city remains in the hands of the extremists. Unlike the east, much of the west is composed of old houses forming narrow alleyways, making the use of armoured vehicles more difficult and promising a tougher fight.

Iraqi special operations forces, regular army and federal police units are taking part in the offensive along with government-sanctioned paramilitary forces, made up mainly of Shiite militias, operating on the city's outskirts.

Mosul, Iraq's second-largest city and the last IS urban stronghold in the country, fell into the hands of the extremists in the summer of 2014, when the group captured large swaths of northern and western Iraq.

Associated Press writer Sinan Salaheddin in Baghdad contributed to this report.</s>HAMAM AL-ALIL, Iraq — U.S.-backed Iraqi forces launched a major air-and-ground offensive Sunday to retake western Mosul from Islamic State militants and drive the extremist group from its last major urban bastion in Iraq.

Ground units pushed into a belt of villages outside the country's second-largest city, and plumes of smoke rose into the sky early in the morning as U.S.-led coalition jets struck militant positions southwest of Mosul and militarized Iraqi police fired artillery.

"This is zero hour and we are going to end this war, God willing," said Mahmoud Mansour, a police officer, as he prepared to move out.

The United Nations warned that hundreds of thousands of civilians trapped inside their homes in Mosul "are at extreme risk," with dwindling fuel, food and water and scarce electricity.

Iraq declared eastern Mosul "fully liberated" last month after three months of fierce fighting, but the militants have continued to stage attacks there, including two suicide bombings against government forces on Sunday.

The battle for western Mosul promises to be even more daunting, as the half of the city west of the Tigris River has older, narrower streets and is still heavily populated.

Prime Minister Haider al-Abadi announced the start of the latest operation on state TV. Using the Arabic acronym for IS, he said government forces were moving to "liberate the people of Mosul from Daesh oppression and terrorism forever."

Police units quickly entered the village of Athba, about 3 miles (5 kilometers) southwest of Mosul's international airport, encountering only light resistance. Separately, the Iraqi Army's 9th Division moved into the village of Bakhira, also southwest of the city, the Ministry of Defense said.

The U.S.-led coalition has been providing close air support throughout the 4-month-old Mosul offensive and carried out nine airstrikes against IS near Mosul on Saturday, Central Command said. U.S. special operations forces are embedded with some Iraqi units, and thousands of American soldiers are in Iraq to provide logistical and other support.

"We are very close to it, if not already engaged in that fight," U.S. Defense Secretary Jim Mattis told reporters in Abu Dhabi. He declined to go into further detail, saying he owed "confidentiality" to the troops.

Citing witnesses in western Mosul, the United Nations said nearly half of all food shops were closed and bakeries had shut down for lack of fuel and an inability to purchase costly flour. Prices of kerosene and cooking gas have skyrocketed, and many of the most destitute families are burning wood, furniture, plastic or garbage for cooking and heating.

"The situation is distressing. People, right now, are in trouble," Lise Grande, the U.N. humanitarian coordinator for Iraq, said in a statement. "We are hearing reports of parents struggling to feed their children and to heat their homes."

Peter Hawkins, of the U.N. agency for children, said: "Three out of five people now depend on untreated water from wells for cooking and drinking as water systems and treatment plants have been damaged by fighting or run out of chlorine."

The humanitarian agencies were gearing up to aid 250,000 to 400,000 civilians who may flee because of the fighting, the statement said. The U.N. estimates 750,000 civilians may be left in western Mosul.

Lt. Gen. Stephen Townsend, a top U.S. commander in Iraq, said the Iraqi forces are an "increasingly capable, formidable and professional force."

"Mosul would be a tough fight for any army in the world, and the Iraqi forces have risen to the challenge," he said in a statement.

Iraqi forces drove IS from eastern Mosul last month, but the militants appear to have left behind sleeper cells to carry out attacks.

Brig. Gen. Yahya Rasool, an Iraqi military spokesman, said a suicide bomber struck a patrol of government-allied Sunni tribal fighters in the Zihoor neighborhood, while another targeted Iraqi troops in Nabi Younis. IS claimed responsibility for both attacks.

Rasool declined to provide casualty figures. Two policemen said one Sunni fighter was killed and nine were wounded in the first attack, while the second attack wounded five soldiers. They spoke on condition of anonymity because they were not authorized to release information.

Iraqi special operations forces, regular army and federal police units are taking part in the offensive along with government-approved paramilitary forces, mainly consisting of Shiite militias, which are operating on the city's outskirts.

Mosul fell to IS in the summer of 2014, along with large swaths of northern and western Iraq.

Associated Press writers Sinan Salaheddin and Qassim Abdul-Zahra in Baghdad, and Maamoun Youssef and Joseph Krauss in Cairo contributed to this report.
Iraq Prime Minister Haider al-Abadi says U.S.-backed Iraqi forces have launched an operation to regain control of western Mosul from ISIL militants. The United Nations says humanitarian agencies are setting up in these older sections of the city where, already, food and fuel supplies are dwindling, running water is scarce, and electricity in many neighborhoods is unreliable for the estimated 800,000 civilians.