The Prime Minister's unsurprising announcement of an Australian military commitment to the US-led anti-Islamic State (IS) coalition answered a few questions and raised others. I think the justification for military intervention in Iraq is relatively straightforward, but the environment within which our forces will operate is anything but.

The mission Tony Abbott described was to 'disrupt, degrade and if possible destroy this movement', a better, more nuanced formulation than Obama's simple 'degrade and destroy'. These are specific military task verbs, and 'destroying' something that is not a static target is very difficult. A movement such as IS can be rendered operationally ineffective to the point that it no longer practically exists but this will take time. Don't expect a neat surrender.

More importantly, the Australian public needs to understand that this mission is simply about targeting IS; it's not about making a better Iraqi nation. I would argue that the multiple identities (to coin a Bernard Lewis term) of Iraqis make it virtually impossible to do this in the short- to medium term, if ever. That doesn't mean we shouldn't contribute to defeating IS, but it does mean we should be mature enough to understand that this is not a binary battlefield — in other words, it's not the Iraqi government vs Islamic State.

Rather, it is IS against Iraqi Government forces, Kurdish fighters, experienced Shi'a militias (who may or may not wear Iraqi military uniforms) who see political advantage in military success and who will leverage this to advance their political aims, Iranian interests providing support to said militias (including their own advisers), and Sunni militias designed to obviate the need for Shi'a-dominated security forces in Sunni-dominated parts of Iraq.

If this appears confusing that's because it is. But it doesn't lessen the threat IS poses, nor does it invalidate our decision to provide aircraft and military advisers to the region.

What it does mean is that the Government should not hide behind bland assurances that we are supporting the legitimate government of Iraq. We will likely be part of a coalition that is supporting forces acting in sympathy with the Iraqi Government — only in some cases we will be supporting actual Iraqi government forces. This is the Middle East, and in many ways this is the best that can be expected. That's why it the Australian public should be brought into the tent regarding the complexity of the societal landscape into which our forces will be deployed.

While the international coalition is being assembled, don't expect it to be anything other than a collection of states acting together for a limited period of time on a specific issue. Tony Abbott was keen to mention the fact that some Middle Eastern states had indicated that they would contribute to military operations, and included Bahrain while keeping a straight face. This is not to belittle tiny Bahrain's contribution, but rather to highlight the irony: this is a state whose minority Sunni monarchy actively discriminates against its Shi'a majority and refuses to undertake meaningful domestic reform which is now taking the fight to a Sunni jihadist group in support of Iraq's Shi'a-majority government. The UAE is also stumping up. This is a country which just a few years ago helped quell Shi'a protests against Bahrain's Sunni Government. On top of that, there is still concern over whether Iran, the regional state which (other than Syria) faces the most direct threat from IS, will be invited to a Paris meeting to discuss the issue. Regional rivalries infect so many aspects of security policy.

This is the environment into which Australian forces are being deployed. None of this is to say that the deployment is unwarranted. What should be articulated by the Government is the fact that we are simply providing a short-term military assistance mission to a deeply flawed nation in a deeply flawed region as part of a coalition, not all of whose members share our liberal democratic traditions. This is going to be the ultimate pragmatist's intervention, and the public should not be left under any false illusions that is anything else.