Once again Australia is heading into conflict alongside the United States. So how does this one compare with some of the more recent military engagements?

We hear constantly from the Government that this is a humanitarian mission, which is nothing like the Iraq conflict of 2003. And in essence that's right.

In fact this conflict has more in common with Vietnam than it does with previous Middle East commitments, but more of that later.

First let's look at what we're sending to this one.

A total of 600 military personnel, 400 of whom are essentially tied to the air mission - six Super Hornet jet fighters (with the possible deployment of another two at some stage in the future), one mid-air refueller, and a sophisticated Wedgetail surveillance aircraft.

Force deployed to combat IS 8 F/A-18F Super Hornet aircraft

8 F/A-18F Super Hornet aircraft 1 early warning and control aircraft

1 early warning and control aircraft 1 aerial refuelling aircraft

1 aerial refuelling aircraft 400 personnel to support air deployment

400 personnel to support air deployment 200 military personnel, including a special forces contingent to act as "military advisors"

The other 200 are special forces, mostly from the 2nd Commando Regiment, who will be engaged in training and advising Iraqi and Kurdish Peshmerga military units. And while some of them will inevitably be despatched beyond the wire, Australian forces will not be conducting standalone combat operations.

In this Iraqi conflict our forces will be deployed under a Status of Forces Agreement with the Iraqi government - an agreement that will give them legal protection and cover deemed acceptable by the Australian Government.

In 2014, Australian forces will be deployed at the request of the Iraqi government. The deployment has the backing of the international community and the United Nations.

In 2003, Australian troops were deployed to remove a government without the sanction of the UN.

That deployment initially included a squadron of some 100 SAS troops and 40 commandos who were tasked with conducting standalone combat operations. We also sent fighter aircraft and naval support.

In Afghanistan in 2001, Australian troops were despatched into what was essentially considered ungoverned territory as part of an internationally backed operation to defeat the Taliban – a regime not recognised as legitimate by the international community.

Special forces were at the forefront of that deployment as well. Initially an SAS team of 150 was sent to operate in southern Afghanistan, in and around Kandahar and Helmand province.

This later expanded to include a reconstruction and mentoring taskforce, artillery specialists, a considerable number of staff embedded in headquarters, two Chinook helicopters, and a C-130 Hercules aircraft on rotation.

At the peak of our engagement there were more than 500 Australians deployed inside Afghanistan and a total of 1,500 deployed across the Middle East.

Apart from the fact that America is again leading the coalition, neither Iraq 2003 nor Afghanistan have much in common with Iraq 2014.

Mission to fight Islamic State similar to Vietnam deployment

A closer comparison, though, can be made with Vietnam.

Like Vietnam, this is a conflict fought against forces that include an invading enemy.

In 1962 the South Vietnamese government – at the urging of the US – invited Australia to help in the fight against the Viet Cong and the supporting North Vietnamese forces coming from north of the border.

In Iraq the bulk of the Islamic State (IS) forces are entering the country from Turkey and Syria. At this stage Australian forces will not be deployed to attack positions in those countries.

In 1962 Australia sent in a team of advisers from the Australian Army training team. At that stage there was bipartisan political and strong public support for the commitment.

By 1965 Australian involvement expanded to including an infantry battalion and then air and naval deployments.

In 1966 that was expanded again to include the deployment of a brigade-sized task force.

As Vietnam showed, every military engagement is fluid and open to review.

"Mission creep" is the term associated with the Vietnam experience, and without clear parameters for this Iraq deployment, some are already wary of the same happening in 2014.

The big and important difference between this and Vietnam is that the fight against IS militants will be conducted with precision weaponry undreamt of in the 1960s, and this conflict also has broad regional backing.

With the exception of Iran, all of the neighbouring countries support the mission.