Australia's Defence Minister says he is optimistic about how quickly a coalition of forces will be able to undermine the Islamic State (IS) terrorist group in Iraq.

Air Force jets have been given the go-ahead to begin targeted strikes against the extremists and are on standby in the United Arab Emirates.

Hundreds of Special Forces soldiers are also expected to be deployed to act as advisers on the ground once they receive final legal approval.

Defence Minister David Johnston has told the ABC's Insiders program he is quietly confident about the mission, adding IS's resources appear to be stretched.

"This organisation has [taken control] in a number of cities a long way from where their supply lines originate back in Syria.

"There's been in recent days some considerable success with the Peshmerga; Sunni tribesmen have sided with those that want to re-establish proper authority in these towns and villages.

"We're quietly confident we have the knowledge, the skill, the ability as a coalition to really start to rein in the sort of rampant behaviour that has gone on in particularly the north and western parts of Iraq."

He said he had been in discussions with coalition generals in the Middle East about the campaign.

"We share optimism about how quickly we can do this, but we must say months and more because we want to under-promise and over-deliver here."

Air strikes are expected to begin within days, though Mr Johnston would not say exactly when.

He welcomed reports on Sunday that a majority of Australians back military action, saying the public is "impressed" by the bi-partisan political support.

"We have seen enough to establish in our own minds as a nation pretty well that this situation in Iraq cannot continue," he said.

Mr Johnston moved to allay concerns over the risk to Iraq's civilian population, given the capacity of IS fighters to hide amongst the general population.

He said while it is a US-led mission, Australia can refuse to strike targets if the risk is too high.

"We do not go forward conducting operations unless our targeting is absolutely certain and we have ascertained exactly the risk levels to collateral damage and civilian population risk," he said.

"We are probably one of the most restrictive in the way we do our business."

Mr Johnston also refuted claims the Iraqi army is not up to the task of combating the militants.

"We wouldn't be undertaking the mission, providing the advice and assistance we are, if we thought it was futile," he said.

"The counterinsurgency service of the Iraqi security forces is very capable and very good and we will be working with them.

"We are optimistic we can put them up in a position where they can re-secure many of these towns."

The US on Friday welcomed Australia's decision to undertake air strikes in Iraq and Prime Minister Tony Abbott received a briefing on the situation from Australian Defence Force (ADF) chief Mark Binskin.

It came as the US-led coalition carried out new air strikes against IS outside a key Syrian Kurdish border town, according to activists and a monitor.