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)

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)

— Iraqi troops and militias aided by U.S. airstrikes broke through a two-month siege of the town of Amerli on Sunday, opening up a humanitarian corridor to thousands of Shiite Turkmen who had been trapped by Sunni militants and deprived of food, water, and medicine.

“Amerli has been liberated,” said Mahdi Taqi, a local official who spoke by phone from inside the town after the army had entered. “There is so much joy and people are cheering in the streets.”

Sunni militants from the Islamic State group, which seized much of northern Iraq in June, had surrounded Amerli, cutting off access to supplies and electricity.

Residents struggled to fight off the militants, but were beginning to die of hunger and disease.

The United Nations Special Representative to Iraq, Nickolay Mladenov, last week warned of an impending “massacre” should Islamic State fighters breach the town.

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)

But a short series of U.S. air strikes on Saturday night appeared to quickly tilt the balance in favor of Iraqi government forces.

The three strikes, plus two more on Sunday, were accompanied by humanitarian aid drops by American, British, French and Australian aircraft, the Pentagon said in a statement.

“These operations will be limited in their scope and duration as necessary to address this emerging humanitarian crisis and protect the civilians trapped in Amirli,” the Pentagon said.

The United States has carried out 120 strikes in northern Iraq since early August. But the Amerli strikes marked the second time this month that the Pentagon has intervened militarily to prevent a jihadist attack on thousands of trapped civilians.

Earlier in August, the U.S. military carried out limited airstrikes and humanitarian aid drops to help Kurdish pesh merga forces open a humanitarian corridor to thousands of members of Iraq’s Yazidi religious minority, who were trapped by the militants on a mountain range in western Iraq.

The long-suffering residents of Amerli, an impoverished farming hamlet, and members of the country’s Shiite majority, had accused Washington of employing a double standard in helping the Yazidis, while Amerli’s siege dragged on for more than two months.

The Pentagon said Saturday night that the U.S. air strikes had destroyed three Humvees, an armed vehicle, a tank and a checkpoint belonging to the jihadists.

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)

Iraqi government officials, Shiite militia leaders, and Kurdish pesh merga forces said a coordinated ground assault to break through Islamic State-held territory around the town began several hours before that, after nightfall in Iraq on Saturday.

On Sunday, an Iraqi television channel belonging to a Shiite militia broadcast footage of its fighters and Amerli residents embracing and crying.

“Our morale is very high. We resisted these people and we won,” said Taqi, the local official. “Now all we need is food and water.”

Fighting continued to rage in neighboring Sunni towns on Sunday night. Residents said the road out of Amerli was still too dangerous for them to evacuate.

Mehdi al-Bayati, an activist in Amerli, said his nephew had been killed by a sniper earlier in the day when he tried to flee by way of a neighboring Sunni village, Suleiman Beg.

But the presence of Shiite militias battling their way through nearby Sunni towns also underscored the potential for revenge attacks, Sunni political leaders and local residents said Sunday.

At least three of Iraq’s most notorious Shiite militias, which fought U.S. forces and killed thousands Sunni civilians during the eight-year U.S. occupation of Iraq, are playing a lead role in the ground offensive.

“I’m happy that the siege has been broken, but I would have been happier if it was achieved by the military alone, and not by the militias,” said Emtashar al-

Samarra, a Sunni member of parliament from Salahuddin, the province where Amerli is located.

“Our main concern now is that these militias, empowered, will punish innocent Sunni people for crimes committed by daaish,” said Samarra, using an Arabic acronym for the Islamic State.

One Shiite militia commander reached by phone on Sunday said his men were fighting their way into Suleiman Beg amid booby-trapped houses.

“God willing it will be fully liberated soon, too,” said Kadhem al-Essawi, a high ranking commander in the Peace Brigades, a militia formerly known as the Mahdi Army.

Since the rise of the Islamic State, rights groups have accused the Shiite militias of reviving old tactics of killing and kidnapping Sunnis, a practice that defined Iraq’s worst period of sectarian bloodletting in 2006 and 2007.

The Islamic State, which has used car bombs and suicide bombers in attacks on Shiite civilians and security forces, has claimed to have executed thousands of Shiites since seizing control of the northern city of Mosul and other territory in June.

On Sunday night a Humvee packed with explosives rammed into a construction site housing Iraqi security personnel in the western city of Ramadi, Reuters reported. The attack killed 37 people.

In Germany, officials said they will send high-end rifles, tank-busting weapons and armored vehicles to help equip a brigade of Kurdish fighters, the Associated Press reported.

Cunningham reported from Irbil, Iraq. Karen DeYoung in Washington and Mustafa Salim in Baghdad contributed to this report.