Iraqi forces readied on Wednesday for an assault on Mosul airport after blitzing jihadi positions in a renewed offensive to retake the Islamic State group’s emblematic stronghold.

Elite forces reinforced positions that were taken since a fresh push south of Mosul was launched on Sunday while hundreds of civilians fled newly recaptured villages.

“Around 480 people displaced from Al-Yarmuk area are being transferred to liberated areas further south,” the federal police said.

Iraqi forces have retaken a key checkpoint on the main Baghdad highway south of Mosul and the village of Al-Buseif, a natural citadel overlooking the airport and the south of the city.

There were no major operations near Mosul on Wednesday, with Iraq’s new interior minister visiting the village and the defense minister also expected on the front lines.

But Hashed al-Shaabi (Popular Mobilization) paramilitary forces battled jihadis farther west near the town of Tal Afar, which is between Mosul and the Syrian border and still held by IS.

The Hashed al-Shaabi said they blew up at least four car bombs in fighting near Ain al-Tallawi and killed several IS members.

The elite Counter-Terrorism Service (CTS) that retook east Mosul and did most of the fighting since the offensive on the city was launched on Oct. 17 have not yet been brought into action in the latest push.

The interior ministry’s Rapid Response units could also move in on the airport in the coming days, a key target before troops breach the city limits to face the jihadis in the narrow streets of Mosul’s west bank.

Senior U.S .officials this week estimated there were only 2,000 IS fighters defending west Mosul, suggesting the jihadi group had suffered heavy losses in the first four months of the operation.

The U.S.-led coalition, which has provided intensive air support as well as advisers on the ground, said before the Mosul offensive began that 5,000 to 7,000 jihadis were in the city.

AFP reporters saw U.S. forces moving into Al-Buseif on Wednesday in convoys of large military vehicles.

A coalition spokesman acknowledged later that U.S. forces had been shot at and returned fire in the battle for Mosul.

“They have come under fire at different times, they have returned fire at different times, in and around Mosul,” Col. John Dorrian said, declining however to confirm if any U.S. troops had been wounded.

The fate of an estimated 750,000 civilians trapped in west Mosul was a major source of concern as Iraqi forces prepared for what many have predicted could be one of the bloodiest battles yet in the war on IS.

Almost half of the remaining population are children, according to aid groups, and supplies are fast dwindling.

“Daesh fighters have seized all the hospitals and only they can get treated now,” an employee at Al-Jamhuri hospital in west Mosul told AFP by phone, using an Arabic acronym for IS.

The health of many residents had been deteriorating for months under the rule of the “caliphate,” which IS leader Abu Bakr al-Baghdadi proclaimed in a mosque near the same hospital nearly three years ago.

“Even before the hospitals were closed, locals had to pay Daesh sums of money they couldn’t afford,” the hospital employee said.

Medical workers and residents speaking from west Mosul on condition of anonymity said the weakest were beginning to die of malnutrition and shortages of medicines.

Iraqi forces declared the full liberation of the city’s eastern side a month ago but the situation there has remained precarious, with the departure of CTS to the western front leaving a security vacuum.

Around half a million civilians stayed on in east Mosul, making the screening process that would have been necessary to prevent IS members blending in with the rest of the population almost impossible.

Several attacks have already been carried out in “liberated” neighborhoods and on Wednesday, some residents found threatening IS leaflets under their doors.

“Warning! To all residents and those present in the east side, you have to leave the city as fast as possible. Staying exposes you to death and you will be a legitimate target for the mujahideen,” the leaflet said.

While more than 50,000 of the 220,000 people displaced during the first months of the offensive have returned to their homes, some people continued to flee from retaken areas for fear of IS reprisals.

The loss of Mosul for IS would effectively spell the end of its days as a land-holding force in Iraq, with only a few scattered and shrinking pockets of territory left.

U.S. forces have been shot at and returned fire in the battle for Mosul, a coalition official acknowledged Wednesday, as American troops edge closer to the front lines.

The United States currently has about 450 military advisers, most of them special operations forces, supporting Iraqi partners as they try to oust the Islamic State group from their bastion Mosul.

The American troops are not supposed to be doing the actual fighting but in recent weeks have gotten so close to the front that they’ve come under attack, said Col. Dorrian.

Dorrian declined to say if any U.S. troops had been wounded in the attacks.

The Pentagon doesn’t typically provide such figures until later, arguing that to do so would provide the enemy with real-time information.

Dorrian said all efforts were being made to keep U.S. forces out of the fight.

When Barack Obama authorized troops back into Iraq in 2014, he stressed that they would be going there in an advisory role.

“They are directed to try and be positioned where that is a rarity and unlikely to occur,” Dorrian said.

“Sometimes (attacks) will happen. Believe me, our forces are quite capable of defending themselves and they will do so very robustly,” Dorrian said.

Speaking in Baghdad on Monday, the coalition’s commanding officer, Lt. Gen. Stephen Townsend, said U.S. troops are fighting closer to the front lines under authorities first granted at the end of the Obama administration.

But the fact these powers are being used more now may suggest commanders feel they have more leeway under President Donald Trump.

“It is true that we are operating closer and deeper into the Iraqi formations,” he said.

“We adjusted our posture during the east Mosul fight and embedded advisers a bit further down into the formation.”