ON THE face of it, the stunning success of the ISIS offensive in the past ten days defies understanding. How could a band of fewer than 1,000 “terrorists” smash their way into Mosul, put around 30,000 Iraqi security forces to flight in less than 48 hours and take full control of a city with around 2m inhabitants? How could a force that initially numbered not much more than 10,000 storm across north and western Iraq, taking several more towns, including Tikrit, Saddam Hussein’s home, and Tal Afar near the border with Syria, while controlling Falluja and most of Ramadi, both in easy striking distance of Baghdad? How could all this happen when Iraq’s government, which spent about $17 billion on its security forces last year (including support from America worth $1.3 billion), can call on a national army of nearly 200,000 men trained and largely equipped by America, backed up by police and paramilitary brigades of more than 500,000?

The failure of the Iraqi army to fight for Mosul and its subsequent collapse have dismayed the American soldiers and trainers who worked so hard to build a cohesive and politically untainted force from the rubble of Saddam Hussein’s army. Much criticism for the débâcle has been aimed at Barack Obama for withdrawing America’s remaining troops in December 2011, before their mission was completed.

Only some of it is justified. Neither the American nor the Iraqi forces had planned for the sudden departure of some 49,000 military advisers and enablers at the end of 2011. But the main reason for it was the refusal of Iraq’s government to sign a “status of forces agreement” that would have extended legal immunity to American soldiers. Mr Obama, keen to take credit for ending the war and to save money, might have done more to persuade Mr Maliki that he was making a mistake. But Mr Maliki was under pressure from the most powerful Shia leaders underpinning his government, as well as from his allies in Iran, to hurry the Americans out. According to an opinion poll at the time, only 16% of Iraqis wanted the Americans to stay on.

The Iraqi forces in 2011 were still in transition, caught halfway between the military ethos of their American trainers that emphasised initiative at junior officer and NCO level and the highly centralised culture of Saddam Hussein’s army that had been forged in the 1980s during the long war against Iran. The deputy commander of American forces in Iraq, General Frank Helmick, warned at the time that the Iraqis would not be able to maintain their capabilities and equipment, let alone take on new challenges. It was assumed that the Americans would be there to defend Iraq’s borders. The revamped Iraqi armed forces had virtually no air power.

But the growing problems ran even deeper. Well before the Americans left, Mr Maliki had begun to subvert the non-sectarian professional army with its many Sunni and Kurdish officers that in 2008, with American help, had vanquished unruly Shia militias making bloody sectarian mayhem. Shia loyalists were rewarded with high-ranking positions in combat and intelligence units, while at lower levels corruption was becoming rife with commissions being routinely touted for sale. With the Americans out of the way, Mr Maliki’s main concern was to ensure that the army could never become an internal threat to him. So began a steady downward spiral in the quality of the Iraqi officer corps, which saw little need to carry on the rigorous training the Americans set such store by.

In 2013, the London-based International Institute for Strategic Studies reported in its annual “Military Balance” that Mr Maliki, who had made himself de facto minister of defence and interior, had introduced political commissars, known as dimaj, into the force structure. It also noted that “a broad set of problems continue to plague the Iraqi army…weaknesses in management, logistics and strategic planning…the chain of command also stifles innovation and independent decision-making.”

Since 2012, Mr Maliki has increasingly used the army against political rivals, often moderate Sunnis, earning it the label “Maliki’s militia”. This has alienated not only Kurdish soldiers and Sunni Arabs, but also Shias who wanted to be part of a genuinely national army. The consequences have been plain to see in Mosul and elsewhere. Shia troops saw little point in dying to hold on to largely Sunni cities.

They won’t always turn tail

Baghdad would be another matter. It is hard to envisage ISIS taking over, let alone controlling, a city of over 7m people, about 80% of whom may be Shias. Shia militias, perhaps bolstered by units of Iran’s Revolutionary Guard, are likely to fight far more fiercely for it than did the national army in Mosul. They would fight even harder to defend the Shia holy cities of Najaf and Karbala that lie not far south of Baghdad, were they threatened by ISIS (see article).

As far as America is concerned, talk of military collaboration with Iran to beat a common enemy has been overdone. It is far from clear that the governments in Washington and Tehran share the same agenda. Does Iran want to help curb sectarian civil war or foment it? Nor is it evident that the limited action the cautious Mr Obama might contemplate—air strikes, but no boots on the ground—would give America the leverage it would need to force Mr Maliki to change his sectarian ways or to stand down in favour of a less divisive successor. Nor does America want to become the Shia air force. But without American intervention, Iraq’s government will struggle to regain control of its lost areas, making the break-up of the state more conceivable. America needs to find a strategy before it decides what it should do. Iran has much less of a problem.