MOSUL, Iraq — Iraqi troops backed by U.S.-led airstrikes pushed deeper into eastern Mosul on Thursday in a multi-pronged assault after a two-week lull in the operation to retake the Islamic State-held city.

Elite special forces pushed into the Karama and Quds neighborhoods, while army troops and federal police advanced into nearby Intisar, Salam and Sumor neighborhoods. Smoke rose across the city as explosions and machine gun fire echoed through the streets.

Stiff resistance by the militants, civilians trapped inside their houses and bad weather have slowed advances in the more than two-month-old offensive to recapture Iraq’s second largest city, the extremist group’s last urban bastion in the country. It is the biggest Iraqi military operation since the 2003 U.S.-led invasion.

In an interview with The Associated Press on Tuesday, Lt. Gen. Abdul-Wahab al-Saadi, commander of the special forces in eastern Mosul, said his forces have been bolstered by reinforcements and are now less than 3 kilometers (2 miles) from the Tigris River, which slices the city in half. A U.S.-led coalition airstrike this week destroyed the last remaining bridge over the river.