An Iraqi places a flowers on an impromptu shrine outside a Baghdad shopping mall targeted last Sunday by a suicide bombing claimed by the Islamic State group, in the Karada neighborhood of Baghdad, Iraq, Saturday, July 9, 2016. The truck bombing which killed at least 186 people was Iraq's deadliest bombing since the 2003 U.S.-led invasion of Iraq. (AP Photo/Hamza Hendawi)
An Iraqi places a flowers on an impromptu shrine outside a Baghdad shopping mall targeted last Sunday by a suicide bombing claimed by the Islamic State group, in the Karada neighborhood of Baghdad, Iraq, Saturday, July 9, 2016. The truck bombing which killed at least 186 people was Iraq's deadliest bombing since the 2003 U.S.-led invasion of Iraq. (AP Photo/Hamza Hendawi) Credit: Hamza Hendawi

Iraqi forces recaptured a northern air base from the Islamic State group on Saturday, a victory hailed by the prime minister as a key step ahead of the long-awaited operation to retake the northern city of Mosul.

In a statement issued on his website, Prime Minister Haider al-Abadi described the air base in the town of Qayara as an “important base to liberate Mosul,” and called on Mosul residents “to get ready for the liberation of their areas.”

Mosul, Iraq’s second largest city, fell to ISIS militants in the summer 2014.

But retaking Mosul itself is not likely to come anytime soon. It will be an enormous undertaking for Iraqi troops, even though they are backed by airstrikes from the U.S.-led coalition and have been joined by pro-government fighters – mostly Shiite militias.

An Associated Press video of the fighting showed government troops rocketing ISIS positions and black smoke pillowing up in the distance. Troops backed by armored cars were later seen marching inside a date palm grove.

But despite recent territorial losses in both Iraq and Syria, where the group has established its self-proclaimed caliphate, ISIS has demonstrated its continued ability to launch offensive attacks in Iraqi government-held territory and beyond. The militants still hold large pockets of territory in northern and western Iraq.

On Friday, the prime minister accepted the resignation of Interior Minister Mohammed Salem al-Ghabban. Hours earlier the prime minister fired Baghdad’s security chief over the attacks that hit in or near the capital during the past week.

Al-Abadi described the recent attacks as the militants’ response to Iraq’s “great victory in Fallujah, which stunned the world.”