Yankaja, Iraq: Iraqi troops, Kurdish fighters and Shiite militiamen backed by American strikes pressed a fightback against militants on Monday, buoyed by breaking the 11-week siege of a Shiite town.

The breakthrough in the operation to dislodge militants threatening the town of Amerli is the biggest offensive success for the Iraqi government since militants led by the militant Islamic State of Iraq and the Levant (Isil) group overran much of the Sunni Arab heartland north and west of Baghdad in June.

It came as the United States carried out limited air strikes in the area, the first time it has expanded its more than three-week air campaign against Isil beyond the Kurdish-controlled north.

The mainly Shiite Turkmen residents of Amerli were endangered both because of their faith, which the militants consider heresy, and their resistance to the militants, which has drawn harsh retribution elsewhere.

UN Iraq envoy Nickolay Mladenov had warned that they faced a “massacre” by the besieging militants.

Iraqi forces kept up the momentum of their advance on Monday, with Kurdish peshmerga fighters and Shiite militiamen retaking Sulaiman Bek, a town north of Amerli that had been an important militant stronghold.

“Sulaiman Bek is under the control of the combined forces,” but there is still danger from bombs the militants may have left behind, said Shallal Abdul Baban, the official responsible for the nearby Tuz Khurmatu area.

A peshmerga officer and another local official both confirmed that Sulaiman Bek had been retaken.

Iraqi soldiers, peshmerga and Shiite militiamen have also surrounded the nearby town of Yankaja and were pounding it with artillery and machinegun fire as they fought to retake it from militants, an AFP journalist reported.

The operation to free Amerli was launched on Saturday after days of preparations in which Iraqi security forces, Shiite militiamen and Kurdish fighters deployed for the assault and Iraqi aircraft carried out strikes against militants.

The government’s reliance on Shiite militiamen in this and other operations poses serious dangers for Iraq, risking entrenching groups with a history of brutal sectarian killings.

The United States said it had carried out a total of four air strikes in the Amerli area, expanding its air campaign outside northern Iraq.

In doing so, it is supporting operations involving militia forces that previously fought against US troops in Iraq.

Australia, Britain, France and the United States have also airdropped relief supplies to Amerli.

But Western aid for Amerli was slow in coming, with the burden of flying supplies and launching strikes in the area largely falling to Iraq’s fledgling air force.

Meanwhile, pledges to provide arms to Iraq’s Kurds, who are battling militants in northern and eastern Iraq, continued to pour in.

Germany will send anti-tank rocket launchers, rifles and hand grenades to support Kurdish forces, the German defence ministry announced on Sunday.

Chancellor Angela Merkel was to set out the plan at a special session of the lower house of parliament later on Monday, after which lawmakers were to hold a non-binding vote.

Kurdish forces backed by US air support have succeeded in clawing back some areas of the north that they lost to the militants last month.

The US military said Sunday that it had carried out an air strike against an armed Isil vehicle near Iraq’s largest dam, north of the militant-held northern city of Mosul.

Kurdish forces and elite federal troops retook the dam after briefly losing it to the militants earlier in August, securing the source of much of the power and irrigation water for the region around Iraq’s second city.

West of Baghdad, two suicide bombers targeted security forces in the city of Ramadi on Sunday, killing 13 people and wounding 17, police and a doctor said.

Isil and its allies control a large swathe of northeastern Syria as well as of northern and western Iraq.

Washington has said that operations in Syria will be needed to defeat Isil, but has so far ruled out any cooperation with the Damascus regime against the militants.

It has, however, attempted to enlist the support of long-time foe Tehran, a key backer of Syrian President Bashar Al Assad.

US Secretary of State John Kerry has urged “a united response led by the United States and the broadest possible coalition of nations” to combat Isil.