A member of the Iraqi security forces secures a building on the front line in Mosul's Old City. Troops launched a push from the northwest early Thursday in an effort to ramp up the offensive to dislodge the Islamic State from the city. (Ahmad Al-Rubaye/Agence France-Presse via Getty Images)

Iraqi forces opened a new front Thursday in their offensive to retake Mosul, advancing from the northwest in a bid to add momentum to the grueling seven-month-long battle for the city. 

Troops from the army’s 9th Division and elite forces from the Interior Ministry spearheaded the early morning attack, according to the Iraqi military. 

Islamic State militants are still holding on in a few neighborhoods of western Mosul, after losing control of the east. But the Iraqi offensive, which is backed by airstrikes and military support from a U.S.-led coalition, had slowed in recent weeks. Interior Ministry forces have ground to a halt on the southern edge of Mosul’s Old City, whose narrow streets and winding alleys are inaccessible to armored vehicles.

Given that challenging geography, Iraqi commanders have said they now plan to lay siege to the Old City by attacking from the northwest. But the district remains home to hundreds of thousands of civilians, raising concerns about their welfare as the battle closes in, and food and drinking water become increasingly scarce.  

“The Old City will be isolated and the last target,” said Lt. Gen. Sami al-Aridhi, a counterterrorism forces commander. He said authorities are considering dropping humanitarian aid to families trapped in areas held by the Islamic State. 

Nearly half a million people have been displaced since the battle for Mosul began in October, according to the United Nations. Some have fled to relatives in the city’s east, which is now under the control of Iraqi security forces.

Others have had no choice but to stay in poorly supplied camps south of the city. Aid groups say they expect a new flow of displaced families as Iraqi forces push from the north. 

After a grinding fight, during which Iraqi forces have suffered heavy casualties, commanders are eager to wrap up the battle before the Muslim holy month of Ramadan, which will begin late this month. With many soldiers fasting during the day, the offensive may slow if fighting is still underway when it begins. 

Brig. Gen. Yahya Rasoul, a spokesman for the military, told state television that Iraqi forces were making a “steady advance” in the renewed push. They retook part of the Mushairafah neighborhood on the northwestern edge of the city, the military said in a statement. 

The Islamic State’s capability “continues to wane,” said Maj. Gen. Joseph Martin, commander of ground forces for the U.S.-led coalition, adding that security forces had made “undeniable progress.” 

But the presence of civilians makes it harder to push forward at a steady pace. Iraqi officers say that since a strike on a building in Mosul’s al-Jadida neighborhood in March that allegedly killed more than 100 civilians, they have been under orders to request U.S.-led coalition airstrikes only when absolutely necessary. The U.S. military is investigating the incident. 

Still, the ground troops rely heavily on support from the air, waiting for hazy weather to clear before they launched their attack Thursday. 

Mustafa Salim contributed to this report.