One thing that must be noted is that what’s happening in Iraq isn’t simply a war between the Iraqi government and ISIS. It’s also a war between Shia and Sunni Muslims.
Yes, there are a small number of Sunni Muslims in the Iraq government, and even fewer in the army; though those numbers are simply not enough to change the central reality of this conflict.
Sunni “insurrections” began in 2003 and has been ongoing (if on and off) ever since. In other words, what ISIS is doing is not entirely new.
And before Saddam Hussein was toppled and then executed, the Shia-Sunni war was only kept under raps precisely because of Saddam Hussein Ba’athist/socialist totalitarian regime. And even then there was periodic sectarian violence as well as Ba’athist state violence against its perceived enemies (such as the chemical and biological attacks on the Shia in 1991).
Another basic point is that virtually all the northern and western parts of Iraq have large Sunni populations. So it’s not surprising that ISIS has had successes in that general area; just as Sunni fighters - completely unconnected to ISIS or al-Qaeda - previously had (if sometimes short-lived) victories in Falluja, Tikrit, Mosul and other parts of that general area.
One advantage ISIS has over its many Sunni rivals is that it appears to have more money than they have. It’s widely believed that much of that money is coming from Saudi Arabia (as well as other Sunni states, groups and individuals). Saudi Arabia, of course, has denied these allegations.
One reason to suspect the claim that Saudi Arabia is financing ISIS is that this tribal and aristocratic state is – or could be – under threat from ISIS if it continues with its successes. ISIS would almost certainly attempt to topple the Saudi regimes because it is seen as “unIslamic”, “corrupt” and too friendly with the United States by virtually all Salafists.
Then again, Saudi Arabia has its own Shia problem (primarily in the south); so it may well be the case that the Saudis are playing a dangerous game here in that if the Sunnis (including ISIS) destroy Shia power in Iraq, then that will also prove beneficial to Saudi Arabia.
According to its “city charter”, ISIS wants to make Mosul the capital of its caliphate. On the other hand, because ISIS hasn’t achieved complete control of Falluja, it has been more lenient when it comes to sharia law in that city. ISIS, in fact, shares control (within a military council) in Falluja with various other Sunni groups as well as with Arab tribes.
One further point is that virtually every news piece about ISIS gives a different account of its precise numbers. In the early days, most reports mentioned the number of 5,000 fighters. Then I began to see the number 15,000. And the last report I read (yesterday) put the number at between 2,000 and 10,000.
Other Sunni Factions
Jamaat Ansar al-Islam
Jamaat Ansar a-Islam (JAI) is a direct rival of ISIS; though some members have recently pledged allegiance to the latter group.
The JAI is a rival due a dispute which goes back to the time ISIS was called the Islamic State in Iraq (ISI). And partly because of that former dispute, it has been reported that ISIS arrested and then murdered many JAI members in Mosul and Tikrit.
It’s also been said that this may be the reason why JAI members have decided to ally themselves with ISIS.
Jaysh al-Mujahideen (JAM)
As stated earlier, Sunni “insurrections” date back to 2003. And just as ISIS can trace itself back to Al-Qaeda in Iraq (AQI) in 2004, so the Islamist JAM also dates back to 2003.
It has been reported that JAM has collaborated with the previously-mention JAI is order to forge a more coherent and stronger counter to ISIS, which is deemed to be too extreme by JAM.
JAM is also much more tribal-based than ISIS in that it has forged various links with Sunni tribes in places like Karma and Tikrit.
The Naqshbandi Order
The Army of the Men of the Naqshbandi Order (JRTN) is said to be the second largest (after ISIS) group of Sunni fighters in Iraq. It’s also a primarily Ba’athist outfit. In fact it’s actually led by Saddam Hussein’s former second-in command, Izzat Ibrahim al-Douri.
Despite being Ba’athist, the JRTN still stresses it allegiance to Sufi (Sunni) Islam and frequently refers to “jihad” in its pronouncements. (As Saddam Hussein himself did all the way back to 1979 – i.e., before the first Gulf War in 1990/1.) Nonetheless, the JRTN also stresses the now unfashionable notion (amongst many Muslims) of pan-Arabism, which itself goes alongside Arab/Iraqi nationalism.
Despite its ideological and political distance from ISIS, the JRTN has collaborated with ISIS in Mosul, Tikrit and in the Diyala province of Iraq. That collaboration is an example of Realpolitik as well as a clever military strategy in that it has been said that through such political and military collaborations, the JRTN thinks that it can eventually get the upper hand against ISIS and thus restore Iraq to totalitarian-socialist Ba’athism.
Islamic Army of Iraq (IAI)
The IAI faction army demobilised after the US army withdrawal from Iraq in 2011. It then set up the Sunni Popular Movement, whose primary aim was to create a Sunni Arab federal region within Iraq. (Many Shia Muslims attempted - or wanted – to do the same thing in the period 2003 to 2005/6 and beyond.) The IAI still offers the mainly Shia Iraqi government one of two options. Either it allows a Sunni federal region within Iraq or it will take military control of Baghdad.
Despite the Islamic Army of Iraq (IAI) not being a jihadist or Islamist group (at least officially), it is still collaborating with ISIS.