A revival of Shia Islam across the Middle East ranks highly among the plethora of unforeseen consequences of the Iraq War. As U.S. missiles struck Baghdad on March 20. 2003, signifying the start of major combat operations, few policy makers would have envisaged the sectarian bloodbath which characterizes Iraq today.

The modern Islamic world is 85% Sunni Muslim, whilst the Shia represent a 15% minority. Within this broad Sunni dominance, Shia Muslims enjoy pockets of political authority; indeed, the Islamic Republic of Iran is often viewed as the standard bearer of Shia political and religious supremacy. Yet, it is events in neighboring Iraq which have focused global attention on Sunni-Shia relations. From the ruins of Saddam Hussein's Ba'athist dictatorship, a political vacuum has emerged in which the oppressed Iraqi Shia majority has realized its long-held dreams of emancipation. This development has sparked anxiety among the largely Sunni rulers across the Middle East. On the eve of the January 2005 Iraqi elections, King Abdullah II of Jordon made headlines by annunciating the feared notion of a 'Shia crescent' stretching from Beirut to Baghdad.

The Sunni-Shia schism has its origins in the birth of Islam, and is directly connected to the succession which followed the death of the prophet Mohammed in AD632. Sunni's believe that the choice of Abu Bakr, Mohammed's father-in-law and a leader of the Ummah, as the first Caliph was correct. This is disputed by Shia Muslims who contend that Mohammed selected his cousin Ali ibn Abi Talib as successor. In AD661 Ali was murdered, and his opponent, Muawiya became Caliph. Ali's son, Hussein, refused to accept the legitimacy of the Muawiya branch. In AD680 Hussein and his supporters were massacred near Karbala. These events marked the beginning of the great Sunni-Shia divide, whilst the deaths of Ali and Hussein are regarded as the advent of Shia martyrdom.

Across the modern Middle East, affiliation to Sunni or Shia Islam determines religious freedom. Iran's 99% Muslim population is divided into an 89% Shia majority, and a 10% Sunni minority. The Islamic Republic's constitution declares, "the official religion of Iran is Islam and the doctrine followed is that of Ja'fari (Twelver) Shi'ism". The document also states that "other Islamic denominations are to be accorded full respect", yet this pronouncement is largely meaningless when translated into reality. Whereas Shia religious institutions are promoted, their Sunni counterparts are often actively suppressed. Indeed, in 1993, a Sunni mosque in Sanandaj was destroyed by a Shia mob. Tehran is home to over 1million Sunni Muslims, yet there are no Sunni mosques to serve the religious needs of this community. Consequently, in July 2003, eighteen Sunni parliamentarians took the bold decision to openly criticize the authorities' systematic discrimination of the Sunni community.

Coupled with such religious discrimination, the Iranian government is also accused of political prejudice against the Sunni minority. According to the U.S. State Department's International Religious Freedom Report 2005, "Sunnis have also cited the lack of Sunni representation in appointed offices in provinces where they form a majority, such as Kurdistan province". The constitution prohibits Sunni Muslims from holding the presidency, and in April 2004 a letter from Sunni Majils representatives to Supreme Leader Khamenei denounced the limited Sunni presence in the judiciary and executive.

In terms of Islamic affiliation, Saudi Arabia is Iran's diametric opposite. Shia Muslims number approximately 2 million, and account for a minority 22% of the native population. The Sunni majority predominantly adheres to the Islamic doctrine of Mohammed ibn abd al Wahhab, an 18th century Arab reformer, and Wahhabi Islam is the only officially recognized religion. Sunni numerical dominance has manifested itself in regular persecution of the Shia population. Shia Muslim employment in many government sectors, particularly those pertaining to national security, is restricted, whilst the Shia presence in the oil and petrochemical industries is subject to government limitations. Indeed, the State Department's International Religious Freedom Report 2005 concluded, "members of the Shia minority are subject to officially sanctioned political and economic discrimination".

Such levels of prejudice are also evident in the arena of religious practice. In 2005, Shia observances of Ashura were permitted in the eastern province city of Qatif. This leniency was predicated on the understanding that participants would not stage large public marches, and the celebrations were closely monitored by a large Mutawwa'in presence. Moreover, in areas such as al-Hassa and Damman which are home to large Shia communities, traditional religious practices are restricted, and many travel to Bahrain to mark important Shia celebrations.

Whilst Islamic identity has long determined the experiences of many Middle Eastern Muslims, it is the Iraq War which has bought the Sunni-Shia fissure to world attention. The Shia account for 60% of the population of Iraq, and are mostly concentrated in the area south of Baghdad. The deposition of Saddam Hussein, combined with the Bush administration's democratization policy, provided the essential preconditions for Shia political and economic emancipation. This shift in the balance of power has contributed to Iraq's descent into spiraling sectarian conflict, the outcome of which will effect Sunni-Shia relations throughout the region.

The February 2006 bombing of the Golden Mosque in Samarra unleashed a new wave of sectarian violence. The al-Askari shrine is believed to contain the remains of the 10th and 11th Imams. It is also reputedly the site of the disappearance of the 12th, 'hidden' Imam, Mohammed al-Mahdi, whose return is understood to herald salvation. The destruction of this important Shia site sparked revenge attacks as Shia's in Baghdad struck at least five Sunni mosques in reprisal raids. Following the January 2006 elections, the formation of a government has been consistently delayed by political infighting. It is this vacuum, created by the absence of a viable political and legal infrastructure, which facilitates the perpetuation of sectarian violence.

The religious conflict which has engulfed Iraq since President Bush declared the end of major combat operations in May 2003 has prompted talk of civil war. Saudi Foreign Minister, Prince Saud al-Faisal, and the Egyptian President Hosni Mubarak are among those who believe an Iraqi civil war is imminent. There are additional telling indicators. As violence continues - the deaths of five people in Karbala, the site of two important Sunni shrines, on Sunday, provides yet another example - population displacement is becoming an increasing problem. The latest Iraqi government figures suggest at least 65,000 Iraqi citizens have fled their homes in fear of sectarian attacks. The movement of Sunni Muslims, residing in the predominantly Shia south, to the 'Sunni triangle' around Baghdad provides an instructive case in point.

Viewed through the prism of Iraq's bloody sectarian divisions, the relationship between Sunni and Shia Muslims appears increasingly fraught. However, observers suggest there are causes for optimism. According to Rawan Maayeh, Civility Program Officer at the Foreign Policy Centre, a prominent London think-tank, "a lot of people have jumped on the sectarian divide in Iraq and manipulated it. Politicians have used it to strengthen their own issues". Whilst she recognizes that "a concerted effort to pull the state together, and avoid the danger of collapse" is needed, Maayeh also emphasizes that religiously motivated violence is only the preserve of some organizations. "It is important to break down these groups and not view them as homogenous entities….some groups in Iraq have come together to reject the destruction of religious sites", she said.

A wider regional survey also reveals grounds for hope for the future of Sunni-Shia relations. Hassan al-Banna and Allamah Mawdudi are among a number of prominent Muslim scholars advocating religious unity. Moreover, on an organizational level, research suggests that Hezbollah, the Lebanese Shia movement is gaining increasing respect among Sunni Muslims, many of whom regard it as a legitimate resistance organization.

These indicators are buttressed by global Muslim initiatives to promote religious unity. Indeed, in the aftermath of the Samarra bombing, a cross-section of British Muslims staged a protest in condemnation. Reflecting on the attacks, Dr Akber Mohammed Ali of the World Federation of Khoja Shia Ithna-Asheri Muslim Communities said, "the desecration….is of grave concern not only to Shias, but to all Muslims in the Ummah. Crimes like this are perpetrated by the enemies of Islam and Muslims should not allow such misguided people to cause division among the Muslim ranks".

Such examples of religious unity are undoubtedly encouraging, yet the future of Shia-Sunni relations is inextricably tied to that of Iraq. The emancipation of Iraq's Shia majority has introduced a new dimension to the Islamic balance of power in the Middle East. The Iraqi choice: a power-sharing agreement, or a political system predicated on oppression of a religious minority, similar to that in Saudi Arabia or Iran, will profoundly affect the Sunni-Shia future. The ability of this nascent democracy to emerge from the sectarian bloodbath as a stable, pluralistic society remains, as yet, uncertain.