The terrorist group is using suicide attacks and booby traps to slow down troops.
Iraqi and peshmerga forces faced resistance from Daesh on Monday, as they gained more ground in the terrorist group's last stronghold in the Iraqi city of Mosul. The militants hit back with shelling, sniper fire, suicide car bombs and booby traps.
Iraq's second biggest city was overrun by Daesh in 2014 and the offensive to take it back is being carried out by the Iraqi government, Kurdish peshmerga forces, and an international coalition against Daesh.
"One week into Mosul operation, all objectives met thus far, and more coalition air strikes than any other 7-day period of war against ISIL," the US envoy to the international coalition's against Daesh, Brett McGurk said on social media, referring to Daesh.
The operation to reclaim Mosul may take months and is expected to be the biggest battle in Iraq since the US-led invasion in 2003.
Coalition forces said it had conducted an unprecedented number of strikes on Daesh targets since the offensive began eight days ago.
"There were 32 strikes with 1,776 munitions delivered," against Daesh target between October 17 and October 23, US military spokesman, Colonel John Dorrian told AFP.
Iraqi forces made gains on Mosul's southern front, taking village after village as they work their way up the Tigris Valley. On the northern front, peshmerga forces were closing in on the Daesh-held town of Bashiqa.
But the forces are facing stiff resistance from the militant group that is believed to have around 5,000 soldiers in Mosul, that Daesh leader Abu Bakr al-Baghdadi proclaimed a "caliphate" two years ago.
Daesh outside Mosul
The terrorist group is expanding the area under its control in Rutba, a remote western Iraqi town that borders with Syria and Jordan, from a third to about half, security sources said on Tuesday.
The insurgents attacked the town on Sunday in a bid to relieve pressure on the northern city of Mosul.
Meanwhile, a series of simultaneous suicide attacks by Daesh rocked Kirkuk in northern Iraq on Monday, local security sources said.
Pentagon spokesman Jeff Davis told reporters on Monday said Daesh is recruiting fighters from outside Mosul to reinforce its defence in the city that is currently under siege.
"We see them taking administrative and support personnel, people who are not normally under arms. But they are now arming them. We also see them moving for reinforcement from outside," he said.