Two Iraqi army pilots were killed on Thursday when their helicopter was shot down over the city of Mosul by Islamic State, according to a military statement.
The helicopter was providing air support to Federal Police forces battling Islamic State fighters on the western side of Mosul, the statement said.
It is the first aircraft downed by Islamic State over Mosul since the start of the U.S.-backed offensive on the northern Iraqi city, in October.
Mosul is Islamic State’s last major city stronghold in Iraq. The hardline group seized the city nearly three years ago, declaring from one of its old mosques a “caliphate” that also spans parts of Syria.
Islamic State’s news agency Amaq said the helicopter crashed in al-Ghabat, east of the Tigris river which runs through Mosul. The Iraqi military statement also located the crash on the eastern side, which was recaptured from the militants in January, after 100 days of fighting.
The insurgents are putting up stiff resistance in the remaining district under their control in northwestern Mosul and the densely populated Old City.
The militants are dug in surrounded by civilians, effectively using them as human shields and taking advantage of the narrow streets of the Old City that restrict the movements of the Iraqi forces and limit the use of artillery and air power.
Progress is much slower than in the early phases of the campaign, during which government forces took nearly three quarters of the city within five months.
The front line has hardly moved in the past three weeks, and the militants, along with roughly 400,000 residents, are trapped inside a ring of Iraq troops.
The soldiers expect the militants to fight to the death.
“Daesh fighters are resisting on a professional level because they have no escape routes left,” said policeman Hussein Qassem, using an Arabic acronym for the militants.
“They are resisting until they are killed. God willing we will not leave any Islamic State fighters. We will fight till the end.”
But advances are hard-won and fragile.
On Thursday, members of the Federal Police co-leading the advance said it was not safe to go to Mosul museum, which they had retaken three weeks ago.
“There is a lot of sniper activity over there behind that building,” a third police officer said, pointing towards an area behind the museum about 100 metres (yards) away.
Just days ago, they had taken journalists to the museum, and other areas closer to the front line.
“It’s now only about snipers and car bombs,” said an officer deployed from a Baghdad unit, as gunfire rang out and soldiers took cover among troop carriers and Humvees behind piles of sand. “They don’t have many snipers but they move around.”