He indicated on the ABC's Insiders program that he viewed the ground war as being a "counterinsurgency" - the firmest acknowledgement yet that it could involve a difficult and drawn-out fight marked by guerrilla-style tactics in urban areas. "The counterinsurgency service of the Iraqi security forces is very capable and very good and we'll be working with them more than likely," he said. "We are optimistic that we can put them up in a position where they can resecure many of these towns." It is understood this could mean the Australian special forces work with Iraq's elite Special Operations Forces - the counter-terrorism commando brigade set up by the Western coalition in the wake of the 2003 overthrow of Saddam Hussein. As well as 400 RAAF personnel, the Abbott government has deployed 200 special forces commandos to the Middle East where they are awaiting final orders to enter Iraq and begin an "advise and assist" role with local forces. Iraq has an army of about 270,000 soldiers but by Washington's estimate only about half of the 50 brigades are remotely reliable.

Tens of thousands of Iraqi troops fled in the face of attacks by much smaller Islamic State forces in June and July, largely because of weak leadership, with commanders often abandoning their troops. Experts say that restoring the confidence of Iraqi troops - many of whom are well-equipped and trained - is pivotal to building them up to a force that can drive the militants out of the towns and cities they have seized in recent months. "It's not so much training them in military skills," said Peter Jennings, executive director of the Australian Strategic Policy Institute. "It's more a psychological thing that they can go on the battlefield and prevail. I think it will take at least several months to equip them with that level of confidence." But that also means the Australian special forces will need to be close to the Iraqis when it comes to fighting, said James Brown, a former Australian army officer now with the Lowy Institute. The government has maintained that the Australian advisers will not be on the frontline. But Mr Brown said they would need to be closely involved to be effective.

"You can't get the trust of the Iraqis if you can't get in there with them," he said. "Whatever language the government uses, Australians will be exposed to combat danger." The former chief of army, Peter Leahy, meanwhile took issue with Senator Johnston's assessment and cast doubt on whether the Iraqi government was ready to put the full resources into winning a counterinsurgency campaign, which typically involves a large amount of civil work to win "hearts and minds". Loading "Rather than the Minister talking about counterinsurgency, I'd rather he talk about the re-establishment of Iraqi political legitimacy and restoration of sovereignty over its territory," said Professor Leahy, who now heads the University of Canberra's National Security Institute. "That's a task for the Iraqi government, supported by regional countries. The question is, are they up to it? The Iraqis have to win the allegiance of their own people."