The complexity of the task facing the Obama Administration in putting together a coalition to target radical Islamists in Iraq should not be underestimated. There are so many competing jealousies, so many personal, political and religious agendas, that the seemingly straightforward task of putting together a coalition of states against a murderous band of religious fanatics who recognise no international norms is anything but simple.

The actual plan for addressing the Islamic State (IS) threat will be outlined by President Obama soon, however it appears likely that the coalition will be in three parts:

1. The 'core' coalition: US Secretary of Defense Chuck Hagel has already coined the term 'core' coalition (which in Australia at least brings back memories of 'core' and 'non-core' promises). Not all of these nations will necessarily take part in air strikes but the intimation is that they will be there for the long haul. The list is depressingly familiar: North America, the UK, Australia and some European states as well as Turkey as the only Muslim NATO member. Ankara has done too little to police its border with Syria, thus partly enabling the growth of IS and other noxious Islamist groups.

2. The 'non-core' coalition: Regional states for the most part who, while recognising the threat posed by Islamists, would rather not be seen to be too keen to bomb fellow Muslims, or to bomb them at all. This is partly due to their ingrained desire to buy their way out of trouble, and for some it is the fear that such action will be unpopular domestically and create internal instability. The Arab League has recently issued a strongly worded statement backing action against IS but the gap between the League's rhetoric and action is normally significant.

Saudi Arabia has already used its financial clout to provide US$3 billion worth of French weapons for the Lebanese Army, ostensibly in support of its increasingly bloody conflict with IS and Jabhat al-Nusra elements, but also to bolster it against pro-Iranian Hizbullah forces in Lebanon. Saudi Arabia will also be crucial in trying to convince Iraqi Sunnis to distance themselves from IS and cooperate with a reformed Baghdad government.

3. The 'unmentionable' coalition: For all the talk of the threat to the West from IS, the one country (besides Iraq) which has been actively involved on the ground and which sees IS as a realistic existential threat is Iran. Iran is very much part of the international coalition, but nobody can afford to mention the fact in polite company.

This is a messy coalition and one in which there will be plenty of free-riders and others doing more than their fair share. Yet in some ways this coalition is simpler than those of the past. Obama has largely abandoned America's ideological obsession with democratising the region. As long as IS is dealt with, whether it is done with the help of theocrats, autocrats or democrats matters little in the short term. The challenge for the US is going to be whether the 'non-core' and 'unmentionable' parts of the coalition can reach a modus vivendi, or whether they will revert to type and view everything through a narrow and short-term lens.