As the battle for Mosul enters its fourth month, the U.S.-led coalition has destroyed the last remaining bridge connecting the western and eastern parts of the largest city in northern Iraq.

Held by the Islamic State since June 2014 and besieged by advancing Iraqi and allied militias since mid-October, Mosul is bisected by the Tigris River. Five bridges spanned the waterway, all of which have now been destroyed in an effort to cripple Islamic State resupply efforts aimed at relieving their militants fighting in the eastern part of the city.

On Tuesday, the Islamic State-aligned news agency Amaq said in a statement that the bridge — known as the Old Bridge — was destroyed in an airstrike. The U.S.-led coalition’s spokesman, U.S. Air Force Col. John Dorrian, confirmed Tuesday that the “final bridge” separating the two parts of the city was hit Monday night, but he said the damage could be repaired.

“The government of Iraq will repair the bridge once Daesh has been defeated,” Dorrian said in an email, using another name for the Islamic State.

Brig. Gen. Haidar al-Obaidi from the Iraqi Counter-Terror Services, the premier Iraqi military unit fighting in Mosul, said that the bridge’s destruction will make it “impossible” for the Islamic State to move reinforcements between the two sides of the river.

The bridge, built by the British during their occupation in the years after World War I and treasured by the residents of Mosul for its history and aesthetic aspects, had been featured in an Islamic State propaganda video posted earlier this month. The video, narrated by the kidnapped British journalist John Cantlie, was meant to show how the U.S.-led air campaign had brought additional suffering to the civilian residents of Mosul by damaging the city’s infrastructure.

In an effort to stop Islamic State forces from taking ground or moving their suicide vehicles into position, the U.S.-led air campaign has conducted numerous “terrain denial” strikes in Mosul, meaning instead of targeting ISIS fighters and vehicles, U.S. and allied aircraft drop munitions on roads and other infrastructure to prevent the militants from using them.

In November, a spokesman for the United Nations’ International Organization for Migration told reporters in Geneva that the destruction of bridges could hamper the escape efforts of the hundreds of thousands of civilians still trapped in Mosul. More than 60,000 residents have already fled the fighting, resettling in temporary desert encampments on the outskirts of the city.

The destruction of the Old Bridge comes as the Iraqi drive into Mosul appears to have stalled. Dorrian said, however, that the Iraqi forces are “conducting a tactical refit to re-position forces, resupply and assess their operations before they push further.”

The fight for Mosul began with a series of victories as a roughly 100,000 strong force of Iraqis, allied militias and Kurdish fighters encircled the city, clearing out small hamlets and moving across open desert as they approached its boundaries. Backed by U.S. airpower and advisers, assigned to help with battlefield intelligence and directing airstrikes, the Iraqi Counter Terror Services then pushed into the eastern part of the city, clearing out militants block by block but taking heavy casualties as the Islamic State used the narrow roads and rooftops to launch attacks with bomb-laden suicide vehicles and snipers.

The United Nations Assistance Mission for Iraq reported that nearly 2,000 Iraqi and Kurdish forces were killed in November, but drew fire from the Iraqi military, which said the U.N. was inflating the numbers of Iraqis killed and wounded. In a statement, the Assistance Mission acknowledged that the numbers were largely unverified and said it would stop releasing them.

Missy Ryan in Washington and Mustafa Salim in Baghdad contributed to this report.