Iraqi Kurdish forces, which have been thrust into the vanguard of the battle against jihadists, fared well maintaining security in their autonomous region but face a daunting task fighting the militants.
Famed as guerrilla fighters during their decades-long struggle for self-rule, the Kurdish peshmerga forces are now made up of a new generation of recruits without the battlefield experience of their forebears.
"Training is very limited by Western standards," said Michael Knights, a fellow at The Washington Institute for Near East Policy.
"Armament is uneven," with some units having body armour, vehicles and some heavy weapons, while others are part-time volunteers who may even have to provide their own gear, he said.
And they face a formidable foe in the Islamic State (IS) jihadists, who spearheaded a sweeping assault that overran swathes of territory north and west of Baghdad in June, and who have combat experience from the civil war in neighbouring Syria.
Some Iraqi government forces simply abandoned their equipment and fled, boosting the arsenal of the advancing militants.
The jihadists are "well-trained, and they have a lot of weapons they captured from the fleeing Iraqi army," said peshmerga Major General Sardar Kamal.
And IS "had the element of surprise to begin with," he said.
Now, American air strikes and international arms deliveries to the Kurds are helping to tilt back the balance.
"With air support, with some intelligence and targeting help from the US and... more equipment and ammunition, they're far better off," said Anthony Cordesman of the Centre for Strategic and International Studies.
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"But they're not a force that was really designed or ready to deal with the Islamic State forces on their own."
Knights said that the peshmerga, which means "those who face death" in Kurdish, deserved their historic reputation but stressed that did not necessarily prepare them for the current conflict.
"Their reputation as guerrilla fighters was earned and can never be challenged," he said.
"But this reputation has been misapplied to a new generation who never were guerrillas, whilst it has been wrongly assumed that the guerrilla experiences of older peshmerga leaders means that they are good at modern light infantry fighting."
Kurdish forces are also far more thinly stretched than they have been in the past.
When the jihadist-led offensive swept aside government troops in June, the peshmerga stepped into the breach across a swathe of territory stretching from the border with Syria in the west to that with Iran in the east -- areas they want to incorporate into their autonomous region over Baghdad's strong objections.
While the move brought them closer to the realisation of a decades-old nationalist dream, it also left the Kurdish fighters defending a much larger area.
Previously, "the only thing they had to hold were major crossing points" between their three-province autonomous region and the rest of Iraq, said Cordesman.
Holding "a very large border area against the forces of the Islamic State is a lot more demanding, and... is a more difficult tactical situation," he said.
When the jihadists went back on the offensive earlier this month, driving east towards the Kurdish capital Arbil, peshmerga forces were pushed back before Washington ordered air strikes and Western governments rushed in arms.
To defeat IS, the Kurds will either "need more troops, more equipment, more training, and crucially more money to pay for it all," or the direct intervention of foreign troops, said John Drake, a security analyst with the AKE Group consultancy.
But the help given to the Kurds has sparked resentment among other Iraqi forces that are battling the jihadists and are also calling for Western assistance, especially air support.