There's concern over the readiness of New Zealand-trained Iraqi fighters as things turn ugly in the fight to recapture a city from Islamic State.
An operation was launched on Monday to liberate the city of Mosul, which has been under Islamic State (IS) control for two years.
International security expert Paul Buchanan told Newshub the Iraqi troops face a tough battle.
"The point of concern is the challenges that they are confronting, in the form of very seasoned and hardened Daesh (another name for IS) fighters compared to the novices that are being produced by the Australians and the Kiwis and others."
Prof Buchanan said the fight will be a test of whether the professionalism of the Anzac military has rubbed off on the Iraqi soldiers.
"The test of the mettle of the New Zealand-trained Iraqi defence forces will be when they come under fire," he said.
"One can only hope the professionalism of the New Zealand defence forces rubs off on the willpower of the Iraqi soldiers to fight."
Prof Buchanan says western military planners are bracing for a long fight, based on Fallujah, but Mosul is different.
"In Mosul, the population is about 40 percent Kurdish and are quite opposed to Daesh's occupation to that city, and in fact have engaged in acts of armed resistance to it."
He says IS fighters could strategically retreat, to protect the terror organisation's capital, to the Syrian city of Raqqa.
Seven villages that form a defensive ring around the city have already been taken however troops are facing strong resistance from an estimated 4000 IS fighters defending it.