As Iraqi troops help liberate the besieged town of Amerli, Australia joins the U.S. and other Western nations in carrying out airdrops of humanitarian aid and military equipment to Kurdish fighters in northern Iraq. (Reuters)

The long-suffering residents of Amerli, an impoverished town in northern Iraq that has been besieged by Sunni jihadists for two months, were relieved Saturday that help had finally arrived.

Militia leaders and government officials said a coordinated offensive to clear the Islamic State-controlled towns around Amerli — and eventually the siege’s front line — began after nightfall in Iraq on Saturday.

Amerli residents and local officials said Friday and Saturday that reports of the offensive, as well as U.S. airstrikes against Islamic State militants and aid drops to residents, have boosted morale in the Shiite town, which has accused Washington and Baghdad of failing to stop the siege.

Karim al-Nouri, a high-ranking official in the Badr Brigades, a large Shiite militia, said that around 7:30 p.m., thousands of the militia’s fighters moved toward the nearby Sunni town of Suleiman Beg, thought to be under the Islamic State’s control. Nouri said the operation was carried out in collaboration with other armed groups, the Iraqi air force and army.

“We are moving from all sides,” he said.

The Iraqi military deliver aid and evacuate vulnerable residents from the town of Amerli in northern Iraq, which has been besieged by Islamic State militants for the past two months. The U.N.’s representative in Iraq, Nickolay Mladenov, expressed alarm on the situation and warned of a possible massacre should the Islamist militants overrun the town. (Iraqi MOD via YouTube)

The U.N.’s special representative to Iraq warned last week of a potential “massacre” if the militants manage to enter Amerli, which is home to members of Iraq’s Turkmen ethnic minority.

More than 20 people have died of hunger and dehydration in the town in the past two months as residents struggled to fight off the attackers, local activists say.

On Saturday, Rafid Moussa, a helicopter co-pilot with the Iraqi air force who said he has flown aid drops and evacuation missions into Amerli, described an isolated population of “simple” farmers desperate to escape.

“We open only one door, and we don’t let the stairs down,” Moussa said of the rescue missions. His account was borne out by videos he had filmed showing villagers running between mud-brick homes toward the helicopter, frantic to board it.

The helicopter stays on the ground for five minutes, and the crew takes only women and children, Moussa said.

Rescues and aid drops had been limited, and Iraqi air force strikes have failed to open a humanitarian corridor out of the town. But local residents and fighters in the area described an uptick in attacks targeting militants, with more than half a dozen airstrikes outside the town Friday, raising people’s spirits.

“Even though people are hungry, when they see the airstrikes, they know that someone is doing something to help them, and this will end,” said Mehdi al-Bayati, a local principal-turned-activist.

This video released by U.S. Central Command shows a U.S. airstrike against an Islamic State armed truck near Irbil, Iraq, on Aug. 26. (U.S. Central Command)

An Iraqi Defense Ministry official who spoke on the condition of anonymity because he was not authorized to speak for the ministry said Saturday that the United States had carried out the strikes — a claim also made by Iraqi media and some Amerli residents over the past two days.

Rear Adm. John Kirby, the Pentagon’s spokesman, confirmed in a statement Saturday that the U.S. carried out airstrikes against the Islamic State in northern Iraq. The Pentagon has also confirmed an effort early this month to open a humanitarian corridor to a besieged community near the Syrian border.

Last week, the Salaam Brigades, a Shiite militia, said it had mobilized thousands of fighters to help break the Amerli siege.

Hazim al-Zamili, a Shiite lawmaker who has acted as a “general coordinator” for the Salaam Brigades, formerly known as the Mahdi Army, said Saturday that the militia’s fighters were starting to attack Sunni towns ringing Amerli, in coordination with the Iraqi military and Kurdish pesh merga forces.

The militia has tried before to end the siege. Zamili predicted its fighters would break through this time in a matter of days.

Erin Cunningham in Irbil, Iraq, and Mustafa Salim in Baghdad contributed to this report.