They control territory the size of Jordan or Pennsylvania. With oil. And they took this territory blindingly fast.
They crushed the Iraqi Army and took their weapons. The Peshmerga didn’t do much better.
Can they be beaten?
At the moment it is a very real possibility that in 10 years time the map of the middle east will be exactly like the de facto map today – containing a large Sunni Caliphate in the area that used to be Western Iraq and Eastern Syria. A Taliban-esque state that is the launch pad for terrorism and suicide attacks across the region and a staging-post for longer range attacks into Europe, Russia and even the US.
It is likely that such a “state” would be smaller than it is today as Kurdish & Iraqi forces take back ground, but unless specific steps are taken this is exactly how the status quo will very likely pan out.
How can the creation of Jihad-istan be prevented?
1) Given that no Western ground troops will be deployed in any real numbers, the Kurdish and Iraqi forces need to play this role with Western air power playing a role as their air force. Very significant material support will need to be provided to these two armies to allow them to take the upper hand, while air attacks gradually degrade the heavy equipment that ISIS have taken from the Iraqi army in recent months and are buying with their oil revenues.
2) Air attacks need to be expanded into Syria. This creates huge complications for the west. Especially the US, because this will mean they are essentially fighting on the side of the Assad regime. Western leaders will have to accept this. Publicly they can deny that this is happening and talk harshly about how Assad needs to be deposed, and how the attacks are to support the mythical “moderate” Syrian rebels. This should enable them to survive with dignity largely intact.
3) The above points are relatively easier than the next. They will result in ISIS probably controlling much LESS territory, probably around the relatively inaccessible Syrian-Iraqi border. It will also reduce their financial resources by taking back some of the oil-producing areas they currently control. HOWEVER, they will remain intact as a jihadist state unless the Iraqi government finds a way of making their Sunni population feel that they have a stake in the Iraqi state and that the government in Baghdad isn’t a Shia government but an Iraqi one.
This was achieved during the famous “surge” during the Iraq war. Which was achieved only very partly by US troops and mainly by SUNNI tribal leaders deciding that they did not want to live under Al Qaeda. The Al Qaeda leaders created this dynamic by forcing radical Sharia government on the population. Gradually brutal punishment for crimes like smoking, improper dress etc meant that Al Qaeda lost the support of the Sunni tribes, and IED’s ambushes and assassinations were deployed against Al Qaeda leaders instead of against the Americans.
Sunni tribes are the only ones who can drive ISIS out of the Sunni border region. Partly because one doubts that the Kurdish or Baghdad armies will have the appetite to advance this far, and also because ISIS can only be driven from this region if they aren’t being given sanctuary by the local population.
The removal of Maliki is a good step in this direction. But only a step. The new government and their Iranian sponsors will need to take real action to make the Iraqi government inclusive. Incorporating high-profile Sunni politicians is crucial, and probably by far the most important ingredient in the defeat of ISIS. In many ways this is their last chance to save Iraq from a future of constant war, sectarian violence and terror attacks.