Updated

Iraq's special forces worked Sunday to clear neighborhoods on the eastern edge of Islamic State-held Mosul as bombings launched by the extremist group elsewhere in the country killed at least 20 people.

Here is a look at the main developments on the 20th day of the Mosul Offensive:

OFFENSIVE SLOWS

The Mosul offensive has slowed in recent days as Iraqi forces have pushed into more densely populated areas, where they cannot rely as much on airstrikes and shelling because of the risk posed to civilians, who have been told to stay in their homes.

Some civilians are fleeing the combat zone, while IS militants are holding others back for use as human shields, making it harder for Iraqi commanders on the ground to get approval for requested U.S.-led coalition air strikes. Iraq's special forces are some of the country's best troops, but they still largely rely on air support to clear terrain.

On the southern front, Iraqi forces are still some 12 miles (20 kilometers) from the city center, battling for the town of Hamam al-Alil. Kurdish peshmerga fighters launched mortar rounds and fired heavy artillery at the IS-held town of Bashiqa, about 8 miles (13 kilometers) northeast of Mosul.

RAQQA OPERATION

Iraqi forces could receive a much-needed boost by the opening of a new front against IS in Syria, where a U.S.-backed and Kurdish-led force says it will march on Raqqa, the extremist group's self-styled capital.

The offensives against Mosul and Raqqa, the two largest cities still under IS control, would proceed in tandem, likely forcing the extremists to split their forces between two crucial battles. But the operation in Syria could escalate tensions with Turkey, which views the Syrian Kurdish forces leading it as an extension of the insurgency in its southeast.

IS STRIKES ELSEWHERE

The extremists meanwhile struck far from the front lines with a series of bombings.

The deadliest attack took place in the city of Samarra, 60 miles (95 kilometers) north of Baghdad, which is home to a major Shiite shrine. Provincial spokesman Ali al-Hamdani said the attacker set off a bomb-packed ambulance in a parking lot near Shiite pilgrims before detonating his explosives vest.

The attack killed 11 people, including at least four Iranians, and wounded up to 100 other people. Another suicide attacker rammed an explosives-laden car into a busy checkpoint outside the city of Tikrit, killing at least nine people. IS claimed all three bombings and said the ambulance bomb was set off by a second suicide attacker.

In the capital, Baghdad, a series of smaller bombings killed at least 10 people and wounded 21 others, according to police and medical officials, who spoke on condition of anonymity because they were not authorized to brief reporters. No one immediately claimed the attacks, but they bore the hallmarks of IS.