Taming Mosul
Defeating IS militarily is less about its own strengths and vulnerabilities than it is about the deficiencies of the forces arrayed against it. IS is as strong as the weaknesses of the failed states whose collapse into "savagery" has left room for it to take root and grow.

Iraq and Syria have to be the primary focus, as the commander of Coalition forces, Lt Gen Sean MacFarland, spelled out in February 2016:
"The campaign has three objectives: one, to destroy the Isil parent tumour in Iraq and Syria by collapsing its power centres in Mosul and Raqqa; two, to combat the emerging metastasis of the Isil tumour worldwide; and three, to protect our nations from attack."

It goes without saying that Coalition air strikes, deadly and effective as they are, have their limitations. Only in co-ordination with cohesive, motivated ground forces can the territory taken by IS be regained. And that's the crippling problem, in both countries.

All of which does not augur well for the sound retrieval of remaining Sunni hotbeds where IS is dug in in Iraq, such as Falluja - barely 30 miles from Baghdad - and above all, Mosul, 10 times the size of Ramadi.

Surprisingly, given the presence of literally hundreds of competing rebel factions, it's in Syria that the chances of making serious progress against IS may be greater, though still not great.

The IS imperative has spurred all the outside parties involved there, including the Americans and the Russians and their regional and local allies, for the first time to put serious weight behind a truce and a negotiated settlement between rebels and regime.

The idea and driving motive is that all parties would then be free to turn on IS, and, to be consistent, also al-Nusra Front, because it belongs to al-Qaeda. It may seem like a long shot, but the US seems to be pushing very hard indeed, making things happen that have proven intractable for nearly five years.

If all the parties - the rebel groups, the Kurds, regime troops and militias, and their outside allies including the Coalition and the Russians - can somehow be reconciled and turned against IS, its chances of surviving for long in Syria would not be great.

Its only real conurbation there is Raqqa. It is much less deeply embedded in the Sunni population in Syria than in Iraq. Disgruntled Syrian Sunnis have many other vehicles for pressing their grievances against the regime.

So it keeps coming back again to Iraq, and specifically, to Mosul. Ten times the size of Raqqa. And that's not the only reason for its significance.

"Mosul is the beating heart of IS," says a senior Western official in northern Iraq. "IS is essentially an Iraqi creation. The tragic reality is that at the moment, it is the main Sunni political entity in Iraq. From the West, it's looked at as a kind of crazed cult. It's not. Here in Iraq it represents an important constituency. It represents a massive dissatisfaction, the alienation of a whole sector of the population."

"That's not to say that the people in Mosul are enthusiastic about IS, but for them, it's better than anything that comes from Baghdad."

The word in both Baghdad and northern Iraq is that the Americans are pushing seriously hard for a Mosul campaign by the end of 2016, with President Obama's departure in mind. That may not be possible, given the difficulties involved in assembling credible ground forces, as well as severe financial crises affecting both Baghdad and Kurdistan.

But if it does go ahead, the fear is that wrongly-conceived short-term victory, if it is achieved, will turn into long-term disaster, given the total lack of national reconciliation between Sunnis and Shia in the wake of the sectarian carnage that followed Saddam's overthrow in 2003.

Sunni grievances in Iraq are such that if IS did not exist, it would have to be invented. Without reconciliation and a sense of Sunni empowerment and partnership in a national project, IS in some shape or form will always be there, just as the Taliban are now resurgent in Afghanistan despite everything that was done to oust them.
But the Iraqi expert on radical movements, Hisham al-Hashemi, believes that IS could be badly damaged if the Coalition succeed in one of their top-priority tasks - to kill Abu Bakr Baghdadi.

Leaders have been killed before, and replaced with little obvious effect on the course of history. But Hashemi believes Baghdadi is different.

"IS's future depends on Baghdadi," he says. "If he is killed, it will split up. One part would stay on his track and announce a new caliphate. Another would split off and return to al-Qaeda. Others would turn into gangs following whoever is strongest."
"The source of his strength is that he brought about an ideological transformation, blending jihadist ideas with Baathist intelligence security methods, enabling him to create this quasi-state organisation."

Hashemi believes only Baghdadi can hold it together. There have been numerous false reports of him being hit, but he appears to be stubbornly and elusively still alive, not seen in public since that mosque appearance in early July 2014.
The Americans are unlikely to rest until they have killed Baghdadi, not least because of their belief that he personally repeatedly raped an American NGO worker, Kayla Mueller, and then had her killed in early 2015.

But even if they do get him, and even if IS does break up, the Sunni problem in Iraq will not go away.