The worst moment for Rislat Shirkani came on the long frightening trek away from the bone-dry ridges of the western Sinjar mountains, where she and thousands of Iraqi Kurds had fled last week from the relentless advance of an insurgent Islamic army bent on mass destruction.

They had been walking for hours along bleak, winding mountain paths when Shirkani saw a mother carrying a dying baby, its face cracked and bloodied from the scorching sun.

“Her baby was dehydrated, as dry as an empty sieve with blood spilling from his lips,” said Shirkani, 30, weeping as she recalled the sight.

“The mother did not know what to do for him as he died, so she placed his body on a rock and walked on.”

Driven from their homes by the rampaging Sunni jihadist group known as Isis, afraid to return for fear of execution, the refugees from Iraq’s latest outbreak of sectarian mayhem were forced to leave their dead unburied as they limped across the desert into Syria in search of relief.

“They were horrible days on the mountain,” sobbed Shirkani, after Kurdish activists guided her group along the Nahr al Khabur River in Syria and back into a safer area of northern Kurdistan.

“People were constantly searching for a drop to drink in places that had no water.”

Shirkani is a member of the Yazidi sect whose colourful mixture of religious beliefs — including a deity known as the Peacock Angel — has been labelled “satanic” by Islamic militants. The Isis vow to purge Iraq of “non-believing” Yazidis and Christians en route to its ultimate confrontation with the hated Shi’ite regime in Baghdad has confounded western attempts to avoid yet another unwinnable war in a region seemingly immune to peace.

Unable to ignore the humanitarian plight of tens of thousands of helpless Kurds — and the prospect that hundreds of American citizens in larger Kurdish towns might be caught up in the battle — President Barack Obama last week sent in airstrikes in what amounted to an embarrassing collapse of his Iraqi disengagement policy.

As US navy fighters and missile-carrying drones pounded IS forces around the Kurdish city of Erbil, where the United States has a consulate, Obama pledged further strikes to break the siege of the Sinjar mountains and reverse the militants’ advance.

In short, America was back where its president emphatically did not want to be: trying to resolve a bitter sectarian conflagration that has burnt for more than a decade and was supposed to be under control when Obama had ordered the withdrawal of American troops in 2011.

As refugees continued to stream from the mountains yesterday, Obama and David Cameron spoke on the telephone about getting vital supplies to those still trapped and bringing them to safety.

Two C130 Hercules aircraft have left Britain and the first was expected to deliver an air drop last night.

Britain was said to be considering deploying members of its special forces to assist if the humanitarian crisis escalated. They could be tasked with helping to martial refugees through “safe corridors”.

London steered clear of any public military commitment and Obama was placed in the unenviable position of having to resume a war that he had once declared at an end.

THERE was no relief in sight for the thousands of displaced refugees who thronged the streets of Ankawa, Erbil’s Christian quarter, this weekend. Outside St Joseph’s Church, children in bare feet ate stale bread. Men sat in the shade with their families, the few possessions they had fled with stacked on thin mattresses on the ground.

Many of the refugees had escaped Isis attacks on the towns of Qaraqosh, Bartila and Hamdania, previously Kurdish havens where Christians could live freely. “People are hurting here,” said Majed Zora, 50. “They are hungry and thirsty, there’s no medicine.”

Abu Ahmad, a Yazidi originally from Sinjar, works in the Iraqi oilfields at Kirkuk and was trying to locate his family, caught behind Isis lines. Ahmad spoke to someone in Sinjar who said the town was empty and that Isis fighters had given an ultimatum to Christian families in nearby villages to convert to Islam by Sunday or be killed.

Ahmad was also appalled to hear that the insurgents had rounded up 500 Yazidi women and had driven them away. In Baghdad an Iraqi official accused Isis of “vicious plans” to turn the women into slaves.

Many of the fugitives were formerly prosperous middle-class Christians, stunned by the loss of their homes and businesses to the insurgent advance. “They came in and killed people. They gave us 12 hours to leave,” said Layla Mansour, a near-toothless 65-year-old pensioner. Her hand made a cutting gesture across her throat.

The United Nations has labelled the situation in Sinjar and other parts of Nineveh “a humanitarian disaster”.

Yet it was scarcely an unforeseeable disaster and international concern had been more muted when Isis forces seized Iraq’s second city of Mosul on June 10. Insurgents painted “N” (for Nazareth) on the houses of Christian families and then confiscated their properties.

Even when the Sunni jihadists unilaterally declared that an “Islamic caliphate” had been formed stretching from Aleppo in northern Syria to Diyala province northeast of Baghdad, there was little reaction from Americans wearied by Middle East combat and intractable ethnic and religious rivalries.

The pressure appeared to subside when a subsequent Isis advance to the south stalled as Iraqi militias mobilised to protect the holy Shi’ite cities of Karbala and Najaf.

Washington strategists had long assumed that northern Kurdish towns would prove equally resistant to Isis ambitions, not least because they were defended by US-trained units known as peshmerga.

The hardy Kurdish fighters had a long record of resistance to Saddam Hussein, the former dictator, and were believed to be more than the equal of less disciplined Isis insurgents.

Then reports began to reach Washington of peshmerga units withdrawing without a fight. In a surge last weekend Isis units routed the Kurds using artillery, mortars and machineguns seized from Iraqi army bases in Mosul.

The jihadists, thought to number at least 15,000, are also believed to have gathered an arsenal of US-made weapons and military material such as Humvee armoured vehicles, armour-plated bulldozers, night-vision glasses and advanced communications provided to the Iraqi army.

Last week Isis members marched almost unhindered into Sinjar, the home of the Yazidi community. They also occupied at least 15 more towns in the region and seized the Mosul dam, which controls the water supply for a vast area.

If breached, experts said, the dam could unleash a 65ft wave of water that could sweep down the Tigris plain towards Baghdad.

The peshmerga were not the giant-killers their US trainers had imagined. “People are fleeing because there is no trust that the peshmerga can protect them,” noted Yonadam Kanna, the leader of a party representing Iraqi Christians.

Kanna also detected a telling imbalance in the two sides’ approach to warfare. “The Islamic State has much bigger and more powerful weapons,” he told The Wall Street Journal.

“These people want to die and have lunch with the Prophet Muhammad. The peshmerga want to live and go home to have dinner with their wives.”

AFTER almost a decade spent preparing Iraqi forces to be responsible for their own security, US officials found their strategy had turned to dust. The failure of Nouri al-Maliki, Iraq’s Shi’ite prime minister, to establish a government of national unity incorporating Kurdish and Sunni leaders, had intensified ethnic rivalries and opened the door to the IS advance.

“Al-Maliki has replaced professional army commanders with political hacks beholden to him,” said Max Boot of the Council on Foreign Relations in congressional testimony last month. “The Iraqi army’s supply difficulties have been just as drastic. The result has been a catastrophic decline in morale.”

With no one remaining to do his fighting for him, Obama was left with no choice. In a broadcast from the White House on Thursday he announced: “Today, America is coming to help.”

In the short term US bombs may at least help to lift morale. There were cheers in Erbil as news spread that the Americans were sending warplanes, but for many of the thousands of displaced, their old lives may be gone for ever.

The British, American and several European governments have already called on their citizens to leave Kurdistan. Iraq’s Yazidi and Christian minorities see no future in a country that lurches from murderous crisis to crisis.

International companies operating in Kurdistan’s oilfields have evacuated their personnel. There are fears that even if the insurgents are forced to withdraw from Mosul, they will first blow up the dam, which in any event requires a weekly injection of fresh concrete into its structure to keep it stable.

The dam, shoddily built under Saddam in the 1980s, is said by experts to be “at great risk of failure”.

Its destruction could rob half a million people of irrigation and power.

Meanwhile, the Isis militants are taunting the West with lurid threats. They have become adept manipulators of social media, routinely posting images of slaughter, beheadings, crucifixions and purported mass executions. Some wrote anti-American screeds with the hashtag #Killthemwhereverufindthem.

Not for the first time since George W Bush invaded Iraq in 2003, the ghosts of Vietnam hovered over the White House as Obama and his aides struggled to strike a balance between his declaration of war on Isis and his assurances to the combat-fatigued US public that this will not result in yet more planeloads of American corpses returning from a distant desert.

“I will not allow the United States to be dragged into fighting another war in Iraq,” Obama said.

Then he repeated himself for effect: “American combat troops will not be returning to Iraq because there is no American military solution to the crisis in Iraq.”

Stephen Biddle of the Council on Foreign Relations warned: “No matter what the United States does, the Iraq conflict is likely to become a long, ugly, ethno-sectarian civil war whose duration could easily run another 7-10 years.”

Obama warned last night that it would “take some time” to help Iraqis overcome the jihadists.

However, his talk of a “long-term project” to resupply the military and build support among Sunnis was of no comfort to the Yazidi mothers whose babies are still dying on the slopes of Mount Sinjar.

Reporting team: Hala Jaber, Tony Allen-Mills in Washington, Sara Elizabeth Williams and Fazel Hawramy in Erbil, Khaled Sulaiman in Sulaymaniya and Mark Hookham