At this week’s UN meetings the focus will be on the threat of Isis, and how the world will respond. The Australian government has committed to help, but is not describing what lies ahead as “war”. In these circumstances, we must all be clear about the situation we are entering into.

By deploying a 600-strong force to the UAE, along with 8 Super Hornet combat aircraft, a Wedgetail surveillance aircraft and transport aircraft, Australia is signing up to a US-led military campaign in Iraq and most likely in Syria too.

It is ultimately irrelevant what terminology the government chooses to use because the declared enemy, Isis, has already set the terms. They have declared a holy war, and now the international community has responded just as the jihadists wanted. White House press secretary, Josh Ernest, confirmed recently that “The United States is at war with Isil in the same way we are at war with al Qaeda.” And just 13 years after we joined the “war on terror”, Australia is now part of this war too.

The Obama administration has worked in quick-time to piece together a broad-based international coalition ahead of Wednesday’s UN General Assembly meeting. This grouping of allies is much broader than George W Bush’s “coalition of the willing”. The collaboration of 30 countries, including 10 Arab states, will give this action a degree of legitimacy that was lacking from the 2003 intervention in Iraq.

However, as Australia goes down this path it is worth considering the make-up of the international “coalition” and the competing, as well as conflicting, agendas of those involved. We are joining a US-led war on Isis, alongside the UK, France and other western allies. Of the 10 Arab states involved, the Sunni states of Saudi Arabia and the UAE will be the most forthright participants – they appear willing to carry out air strikes.

Outside this formal coalition, Iran is already supporting its Shia allies in Iraq against Isis, while the Syrian government says any military action against Isis in Syria must include them too. So, while Iran and Syria may not be palatable allies for this western led coalition, they are undeniably united against a common enemy.

While it might suit us to imagine this fight in binary terms, a struggle of good versus evil, there is an important point that must not be ignored. This war is pulling together an uncomfortable conglomeration of natural allies and natural enemies on one side and pitting them against an equally messy conglomeration of allies on the other. Within this international coalition there is not even a clear set of values underpinning the agenda and perhaps, more worryingly, there is no clear objective.

Some members of this coalition will be satisfied with diminishing the operational capabilities of Isis. Others will want to see Isis destroyed completely, whatever that means. No convincing argument has yet been made about how bombing specific targets in northern Iraq and Syria will help to destroy an ideology which has spread, cancer-like, radicalising limited but troubling numbers of disaffected young Muslim men and women around the world, including in western Sydney.

Complicating this scenario even further will be the outlying objectives of some members of the international coalition. The Sunni governments of Saudi Arabia and the UAE have long wanted to see off the Alawite dominated regime of Bashar al-Assad, with its allegiances to Shia Iran and Shia Hezbollah, in Lebanon. Speaking on Sunday, Syria’s deputy foreign minister Faisal Mekdad put it mildly when he described that approach as “a very dangerous game”.

It is clear that Australia’s leaders believe this military exercise has good and clear intent, but it will almost inevitably come to be perceived in the region as Sunni Arab states alongside western allies bombing radical Sunni Muslim targets inside Shia dominated Iraq and likely also in Alawite led Syria.

Sounds complicated and potentially disastrous? It is.

As this drags on, there’s every chance the line will become blurred between radical Sunni Muslim targets and other targets in Iraq and Syria. If, for example Sunni tribes in the north-west of Iraq are not brought back into the fold by a more inclusive national government in Baghdad, how then does the coalition distinguish between them and the radicals? The risk is that what we, in Australia, might see as a clear battle-line between Isis and the rest of the civilized world will be understood in a vastly more nuanced fashion in the Middle East. In truth, this war has a multitude of battle-lines and whilst Australia might be clear about where it stands, it will not always be immediately clear where our partners stand.

The Australian government may have deemed that there is simply no other choice than to commit to this. And they would not be alone in concluding that. But if we are going into battle, we should firstly know if this is in fact “a war”, which side we are on and what precisely it is that we are fighting for.