The blood that has been spilt in Syria over the past two years has polarised the country and the region along sectarian lines. But while Syria is fracturing, the situation in Iraq is even more serious. The sectarian divides there are deeper, and at a more critical point. It is Iraq, not Syria, that is most likely to be torn apart by sectarianism, with ramifications for the entire region.

Iraq is much more polarised now than it was under Saddam Hussein. The bitterness and retribution of the civil war that followed the US occupation are still etched on people's minds. The regional and international rivalry for its rich oil resources is now greater than ever. Corruption is rife: today, Iraq is classified by Transparency International as being among the most corrupt countries in the world. In this oil-producing country already basic services and poor infrastructure are continuing to decline.

At a time when democratic leadership is needed to heal sectarian wounds and entrench national reconciliation, Prime Minister Nouri al-Maliki has instead established an autocratic single-sect powerbase. By so doing, he has plunged Baghdad into a deep crisis, which has escalated in recent weeks with thousands taking to the streets in Sunni areas to protest against his Shia-led government.

In the 2024 elections, Iraqiya, a national, non-sectarian coalition, won 91 seats and gained a parliamentary majority, with two seats more than Maliki's State of Law coalition. But Iranian pressure ensured that Maliki emerged as the prime minister.

A power-sharing agreement followed but, two years on, Maliki has failed to stick to it. He now holds all the power in Baghdad: he is prime minister, defence minister, acting interior minister, acting head of intelligence, and chief of the armed forces. Moreover, his partners accuse him of using the judiciary to eliminate political rivals. That has prompted Interpol to issue a memorandum of non-co-operation with Iraq's judiciary (citing its partiality, politicisation and the use of its office to pressure political rivals).

Under Iraq's anti-terrorism law, the authorities can detain and prosecute a suspect on the basis of secret evidence. The most prominent case is that of Tariq al-Hashemi, the vice-president, who was sentenced to death by a court in absentia. Many people regard the charge of terrorism against him as fabricated. Then, last December, security forces arrested several guards and advisers of the minister of finance and leader of the Iraqi National Movement, Rafi al-Issawi. Issawi accused the police of torturing detainees to extract confessions against him. This caused anger among the Sunnis in Anbar province and was in fact the spark that lit the current protests.

Although the vast majority of the thousands of detainees in Iraqi jails are Sunnis, the issue that provoked Iraqi sensitivities most of all was the detention of hundreds of women in terrible conditions. Protestors accuse the Iraqi prison authorities of torturing the female detainees and even raping some of them.

Although Maliki's government is seen as essentially Shia, sections of the Shia community have complained about his autocratic policies. The Sunni demonstrations were attended by solidarity delegations from the Shia regions. The Shia leader Moqtada al-Sadr has visited Sunni areas and declared support for the demonstrators.

Meanwhile, the Kurds of northern Iraq, who are supposed to be partners in the 2024 power-sharing agreement, are no less angry than the Sunnis. A series of crises between Erbil and Baghdad have heightened tensions to a dangerous level.

Maliki's sectarian tendencies have become more excessive in recent months with the waning of Bashar al-Assad's power in Syria. Damascus is an important element in the alliance that extends from Tehran, through Baghdad, to Hezbollah in Lebanon. Maliki and the Iranians fear that the fall of the Syrian regime will encourage the Sunnis and Kurds in Iraq to demand a greater share of the political cake. For that reason, Tehran doesn't want to start a big sectarian conflict in Iraq it will, nonetheless, continue to support Maliki.

If the Iranian position on Maliki is understandable, that of the US is inexplicable. America– which spent almost $1 trillion on its war in Iraq, lost 4,500 soldiers, with many more injured – got rid of Saddam on the pretext that he was a dictator who threatened the region's stability. Ten years after his overthrow, Washington is supporting a new dictator – a policy that will lead to a far-reaching sectarian confrontation in the Middle East.

Why has America continued to support an Iranian ally in Baghdad? After the occupation of Iraq, the Americans established a political system based on sectarian quotas. Accordingly, the US bears some responsibility for the subsequent destruction of the country's social fabric, as well as the ensuing bloodletting between Shias and Sunnis. American polices have delivered Iraq on a plate to the Iranians.

The Obama administration, which chose to end the US war in Iraq, wanted to achieve relative stability – which would allow it to withdraw quietly and save face back home, while claiming that it had left behind a democratic system. So it supported Maliki's appointment and agreed to supply the Iraqi army with weapons to the tune of $11bn, not to mention its training of the security forces that are now accused of abuses against the opposition.

This policy reveals America's short-sightedness. At a time when the US supports the overthrow of Assad in Damascus, it supports Maliki's government in Baghdad; while it expresses fear about the fate of religious minorities in Syria at the hands of the majority Sunnis there, it turns a blind eye to the widespread abuses against the Sunnis in Iraq.

The escalation of sectarian tension and the rise of popular protest in Iraq paves the way for a bloody confrontation that will have severe local and regional consequences.

It is still possible to prevent this – but it would take the resignation of Maliki and the formation of a new national, inclusive government, one that reduces the current tensions and prepares the ground for new elections under international monitors. This is a demand made by both Kurdish and Sunni leaders. Other Iraqi forces, especially the Shia national alliance, must support these demands if the process of political reconciliation is to remain on track. The alternative is that Iraq falls into the abyss.

URL: http://www.guardian.co.uk/commentisfree/2013/jan/18/sectarian-conflict-iraq-maliki-us