“Most of the Sunni leaders were living in another world. They were in a weird state of denial. The Sunnis continued to behave as though they were Iraq.”

Nothing better sums up the dilemma of the Iraqi Sunnis following the US-led invasion of Iraq and ouster of former president Saddam Hussein's Sunni-dominated regime in 2003 than these words of Lakhdar Brahimi, the former UN envoy to Syria, who played a key advisory role in forming Iraq's first government after the invasion.

For most of the last decade Iraq's Sunni minority has stubbornly refused to come to terms with the post-Saddam reality that has enabled the country’s Shia majority to come to power and transcend the past in order to build a future for all Iraqis.

Most Sunnis boycotted the referendum on the post-Saddam constitution on the grounds that it was a recipe for the end of Iraq as a unitary state as it allowed confessional groups, or provinces, to set themselves up as autonomous regions under a federal system.

The Sunni mood of rejection, fuelled by policies of exclusion and discrimination exercised by the newly empowered Shia-led government, has become a policy choice that was first displayed in dismayed opposition and later became actions of violent resistance and persistent rebellion.

By maximising their goals and resorting to violence, the Sunnis alienated moderate secularist Shias who could have partnered with them in a political alliance to challenge the Shia religious groups that took advantage of Sunni extremism to hold onto power.

Since the seizure of Mosul and several other predominately Sunni cities last month, plunging Iraq into a new cycle of sectarian war, the question that has exercised analysts has been the nature of the Sunni strategy to further their cause amid Shia mobilisation to stall the Sunni advance and retake the captured towns.

It is well understood that the policies of marginalisation of the Sunni community by Shia prime minister Nuri al-Maliki, which have isolated the Sunnis politically, are a main factor behind the revolt.

But doubts remain whether resorting to all-out sectarian war spearheaded by the terrorist group the Islamic State in Iraq and Greater Syria (ISIS) will allow Iraqi Sunnis to regain their previously dominant role in Iraq's politics.

Instead, it is feared that the Sunni offensive will only deepen the sectarian schism, further entrench the Shias, and send Iraq down the path of fully-fledged civil war.

The Sunnis face tough questions about their military and political strategy. Baghdad, a city of six million people the majority of them Shias, is unlikely to fall to the Sunni rebels. After absorbing the shock of the defeat, the government forces have also launched a counter-offensive to take back the cities lost to the insurgents.

The deployment of newly bought Russian-made Sukhoi (Su-24) bombers and US manned and unmanned surveillance aircraft will drastically shift the military balance in favour of the government troops.

The Iraqi army may not succeed in putting down the Sunni rebellion, but the conflict could trigger a protracted and costly civil war similar to that taking place in neighbouring Syria.

The Sunni threats to expand to Baghdad and the Shia holy cities of Najaf and Karbala have already inflamed Shia fears and led to mass mobilisation in Baghdad and Shia cities.

Grand ayatollah Ali al-Sistani, the Shia religious leader, has urged all Shias “who are capable of carrying arms to join the government” in the fight against the rebels. With sectarian mobilisation on the rise, hostilities are expected to simmer to a boil and spread across Iraq.

A key mistake committed by the Sunnis is their alliance with ISIS in their drive to fight the Shia-led government. Although the partnership with the murderous organisation, responsible for killing thousands of civilians, mostly Shias, dates back to the beginning of the Sunni insurgency, the new alliance will put the Sunnis at the mercy of the terrorist group.

The declaration of an Islamic caliphate in Iraq by ISIS this week with temporal and spiritual sovereignty will further complicate the sectarian conflict.

One problem is that the Sunnis will be held responsible for the gruesome atrocities which the group is perpetrating in territories under its control, including the summary executions and extra-judicial killings of Shia civilians, police and soldiers, which will deepen sectarian animosity and create a backlash against the Sunnis across Iraq.

Since ISIS spearheaded the offensive dark sectarianism has swept many parts of Iraq, and there are already reports of Shia reprisals against Sunnis in Baghdad and elsewhere. In recent days there have been reports of Iraqi police killing Sunni insurgent prisoners in their custody and the sectarian killing of Sunnis in Baghdad.

A second problem is that the Iraqi Sunnis have different goals from those of ISIS, which now wants all Sunnis to pledge allegiance to its “caliph” Abu Bakr al-Baghdadi.

Few among Iraq's Sunnis are expected to make such a vow, and many have fought ISIS before and are unlikely to endorse either the group’s fanatical strategy or its hard-line tactics.

While some Sunnis will continue to aspire to take back control of the government in Baghdad, most only want an end to their alienation and mistreatment by having an equal share in the power and resources either of a federal or of a unitary Iraq.

Sooner or later, the onslaught on the cities and threats to seize more will prove to be an expensive war of choice boding ill for Iraq’s Sunnis. By taking their anti- government protest movement to a full-scale war, Iraq’s Sunnis are risking not only peace and stability but also the country’s unity.

The Iraqi Kurds have already exploited the turmoil and seized land populated by Sunni Arabs, planning to annex it to the autonomous Kurdistan Region. There is a real danger that the insurgents will end up positioning the Sunnis in a resource-poor canton in the so-called Sunni Triangle in western Iraq and resulting in the de facto partitioning of Iraq.

Seen from this perspective, Iraq's worsening sectarian conflict and the involvement of the ISIS jihadists will have far-reaching implications not only for its people and its neighbours but also for the Islamic world at large.

It may ignite the long-anticipated war within Islam, pitting Shias against Sunnis, on the one hand, and moderate Muslims against radicals, on the other.

The Shia-Sunni split dates back to the 7th century when the Prophet Mohammed died and a debate emerged about who should succeed him as leader of the emerging Muslim community.

The Shias felt Mohammed's successor should be his cousin and son-in-law Ali Ben Abi Talib, while the Sunnis chose one of his faithful disciples and argued that a prominent Muslim leader who would follow the Prophet's traditions should be chosen by consensus.

That political debate and struggle for power has led to a sectarian rift which since then Muslims have never been able to heal.

In Iraq, the Sunnis held power since the British occupation following the collapse of the Ottoman Empire after the First World War. Historians point to the role played by the British authorities in empowering the Sunni elite as a new political class at the expense of the majority Shia population.

By helping the minority Sunnis to dominate the Shias and ethnic Kurds, the British helped set the conditions for today’s sectarianism. While the Sunnis continued to pride themselves on being the guardians of Iraq's unity, Shia disenchantment with Sunni domination and Kurdish secessionism grew.

Many would now argue that the United States aggravated the situation when it invaded Iraq in 2003 and toppled Saddam's Sunni-dominated regime, helping empower the majority Shias through the sectarian-based political process it launched.

The same US-engineered system allowed the Kurds to have a federal region, which they gradually and relentlessly turned into a semi-independent entity.

Shia political forces worked through their monopoly of power and control of the security forces to consolidate power and did little to initiate a process of reconciliation and inclusion.

As a result, the Sunnis felt that they were without effective political representation and subsequently the biggest losers in post-Saddam Iraq.

Yet, Iraq's problems are not simply the results of the failure and follies of US policy and the rise of the Shias and the Kurds’ secessionist ambitions. They are also the inevitable consequences of the Sunnis' maximalist strategy, militancy and lack of a sense of direction and leadership.

The Sunnis have always needed a political compass and roadmap that would define peaceful and democratic alternatives and allow them to voice their grievances and push for full partnership in a multi-sect political process.

There are many secularist and nationalist Shias who are opposed to the exclusion of the Sunnis from government and reject al-Maliki's sectarianism, authoritarianism and heavy-handed style of government.

The Sunnis have common ground with these Shias, who want to build a shared future with their Sunni counterparts. Unfortunately, the Sunnis have failed to reach out to these moderate Shias and make statements about their readiness to work jointly to achieve national goals.

The Sunnis need to work for justice in a participatory political system that includes all sects and ethnicities, but in order to do so they have to come to terms with the Shias and the Kurds.

As Brahimi rightly noticed, they need to acknowledge reality and stop defining themselves as the only true Iraqis, dismissing the Shias as traitors and “Iranian stooges.”

The ultimate solution to Iraq’s problems is a political one, and the Sunnis cannot pursue their goals through violence and territorial gains. The Sunnis refused the idea of power-sharing among Iraq's ethnicities following Saddam's downfall, claiming that the new political system would herald the break-up of the country.

Now by seizing cities they have drawn the lines of a little “Sunnistan.” Worse still, they have put it under the rule of a terrorist group that has declared it to be a Taliban-style mediaeval caliphate.

This article was originally published in Ahram Weekly