The minarets or prayer towers of the Al-Askariya mosque in the city of Samarra, one of the most revered shrines of Shiite Islam, were reduced to rubble yesterday in an act designed to unleash a new wave of sectarian carnage across Iraq. Details of how the attack was able to be carried out are vague at this point. The mosque was supposed to be one of the most carefully defended locations in Iraq due to its religious significance to Shiites and the violence that followed the bombing of its golden dome on February 22, 2006.

In last year’s bombing, alleged Sunni Muslim extremists associated with Al Qaeda overwhelmed the mosque’s guards and rigged explosives in a manner to bring down the dome—one of the landmarks of modern Iraq. The response was a frenzy of Shiite revenge. Militias linked to the main Shiite political parties in the Iraqi government carried out a wave of killings and destruction against Sunni communities. As many as 100 Sunni mosques were bombed and thousands of people were slaughtered by death squads. Shiite members of the Iraqi army and police either permitted or joined in the atrocities. Sunni extremists responded with murders of their own and suicide bombings, which indiscriminately targeted Shiite civilian areas.

Sectarian killings peaked in late 2006, when over 3,000 people were being murdered a month. The United Nations estimates that over 600,000 Iraqis of both denominations fled their homes from February to the beginning of 2007 to escape from the violence being perpetrated by rival religious fanatics.

The danger of another bloody upsurge cannot be underestimated. Al-Askariya is at the very centre of the beliefs of fundamentalist Shiites. It is the ninth century burial site of the tenth and eleventh imams of the Shiite faith and where the twelfth and final recognised imam, Mohammed al-Mahdi, is believed to have disappeared. Shiite theology states that al-Mahdi will return during the time of evil, form an army and restore the rule of the imams. The oppression and injustice suffered by Iraq’s Shiite masses over the past five decades has led to the emergence of various trends of Mahdism, which preach that the Mahdi’s reappearance is imminent.

The two largest Shiite militias in Iraq contain thousands of adherents to Mahdism—including the Mahdi Army militia loyal to cleric Moqtada al-Sadr and the Badr Organisation of the Iranian-linked Supreme Iraqi Islamic Council (SIIC). Thousands more are members of the Iraqi army and police. Mahdi Army and Badr fighters were widely blamed for most of the sectarian attacks on Sunnis following the first bombing of the mosque.

The Shiite-dominated Iraqi government of Prime Minister Nouri al-Maliki issued an appeal for calm yesterday and imposed a 3 p.m. curfew across Baghdad to prevent violence. An additional army brigade has been deployed to Samarra. The leading Shiite cleric in Iraq, Ali al-Sistani, called for “believers to exercise self-restraint and avoid any vengeful act that would target innocent people or the holy places of others”.

Thus far, there have been several reports of Shiite retaliation but nothing on the scale of 2006. In the Baghdad suburb of Baiyaa, a Sunni mosque was set ablaze. Within hours of the attack on Al-Askariya, two mosques in the once mixed city of Iskandariyah had been damaged or destroyed, including the city’s Grand Mosque. One factor in the relatively muted reaction is openly expressed disbelief among Sadrists in US claims that Al Qaeda was behind latest bombing.

Relying on US and Iraqi government sources, the New York Times has provided the only detailed account of what might have taken place. According to the article, a new Shiite-dominated detail had taken over security at the Al-Askariya mosque in the past few days, replacing a largely Sunni force of local police. Sources for the New York Times implied that disgruntled police attacked the new force and assisted Al Qaeda bombers to gain access to mosque and blow up the minarets. Fifteen police have been detained, according to CNN accounts.

The Sadrists, however, have directed suspicion not at Al Qaeda, but at the US occupation forces and the Maliki government who were responsible for the mosque’s protection. Large crowds reportedly gathered at major Shiite mosques in the southern cities of Najaf and Karbala, chanting anti-occupation slogans.

Yesterday, Moqtada al-Sadr explicitly accused the US military of involvement in the bombing. Calling for three days of mourning by both Shiites and Sunnis, he declared the bombing was part of a “cursed American-Israeli scenario that aims to spread turmoil and plant hatred among Muslim brothers”. He called for joint Shiite-Sunni demonstrations “for everyone to witness that the only enemy of Iraq is the occupation and therefore everyone must demand its departure or a timetable for its end”.

Mahdi Army loyalists of Sadr have reportedly established defensive cordons around Sunni mosques in the southern city of Basra to prevent sectarian attacks. Thirty-two legislators belonging to the Sadrist movement have announced a boycott of parliament until all damaged mosques, Shiite and Sunni, are rebuilt and a new security force is assigned to the protection of Al-Askariya. The Association of Muslim Scholars, which represents Sunni clerics, has taken a similar stance to the Sadrists, issuing a statement holding the occupation and government “fully responsible” for the attack.

The allegation that US or US-backed forces were involved in the mosque bombing is not a flight into fantasy. In recent months, the US military has forged alliances with Sunni insurgent groups, nominally to fight Al Qaeda extremists, but who are also bitterly hostile to the Shiite-dominated Maliki government in Baghdad. The US military has made no secret of its plans to eliminate Shiite militias. A bombing that provoked widespread Shiite retaliation would not only provide the pretext for a full-scale assault on the Madhi Army, but could pave the way for closer cooperation with Sunni militia groups.

Whether the US military was directly involved or not, the Bush administration is directly responsible for the continuing sectarian violence in Iraq. From the outset, the US occupation has rested on Shiite fundamentalist and Kurdish nationalist parties and the manipulation of sectarian and ethnic divisions. The last thing that Washington wants to see in Iraq is the emergence of a political movement unifying Shiites, Sunnis and Kurds demanding an immediate end to the presence of foreign troops.