The Iraq, the United States left behind last month is dramatically different from the country it invaded in 2003. Gone are the comforting simplicities of the “war on terror” and democracy building. The geopolitical context that America has bequeathed to Iraq is now defined by five critical challenges.

First, Iraq is at the center of the American-Iranian confrontation; it is the only place where the American military has faced off directly against Iranian-backed militias.

Second, it stands in the middle of the conflict between Iran and Saudi Arabia for regional supremacy. The Saudi royals oppose the current Iranian government but not necessarily the Iranian system itself; they might happily co-exist with a different Iranian leadership, as they did during the 1990s.

Third, as Turkey reasserts itself in the Middle East, both to counter Iran and to promote its own vision of modernising Islamism, Iraq is in the middle once again. Turkey is a patron to the large Sunni-dominated Iraqiya parliamentary bloc and the biggest source of investment in the Iraqi Kurdistan region. And it is intimately involved in the affairs of the Kurdistan Regional Government, the K.R.G., in order to keep close tabs on Turkey’s own Kurdish separatist movement, which is based there.

Fourth, Iraqi Kurdistan is thriving, and will most likely drift toward some form of de facto independence. It is already nearly there. The spectacle of Iraq’s fugitive vice president, Tariq al-Hashimi, holed up in Kurdistan beyond the reach of Baghdad, is the clearest proof. The K.R.G.’s success in providing security and services — in contrast to the central government’s dismal record — is now fueling demands for other autonomous regions throughout Iraq, posing a major challenge to the historically centralized and militarized Iraqi state. Finally, the current atmosphere in the region reeks of an impending sectarian explosion. Shiite-Sunni conflict led Iraq to the brink of all-out civil war between 2005 and 2007. Today, a reprise of that disaster is quite possible. The triumphalism of Shiite politicians masks anxieties about their community’s ascendancy. And the news media, especially Arabic-language satellite channels, are brimming with blatantly offensive sectarian sentiments and contributing to an atmosphere of crisis and impending disaster — prompted in no small measure by the nefarious work of bigoted and ignorant clerics, often inspired by the intolerant ideology of Wahhabist Islam.

The French historian Fernand Braudel used the term “longue durée” to describe how changes in the deep socio-economic and technological structures of civilisations play out over long periods of time. Such shifts are as important in determining the history of societies and nations as major political events and crises.

The Middle East is today experiencing a twofold upheaval of immense proportions: a dramatic acceleration of climate change, water shortages, urban growth, environmental degradation, persistent economic and resource imbalances, and population explosions that coincide with wars, invasions, foreign interventions, civil and religious strife, and mass uprisings. And the longue durée is now exerting its influence on Iraq.

The livelihood of Iraqis is overly dependent on a state that is entirely reliant on a single resource. Agriculture has effectively collapsed; the great river systems of Mesopotamia have shriveled; trade routes based on Iraq’s unique geography have vanished; and transport links have atrophied. Merchants and entrepreneurs are merely recyclers of state-owned and state-generated wealth and a previously open and culturally and religiously accommodating society has been replaced by beleaguered communities locked in laagers. The Arab successor states to the Ottoman Empire have all proved to be unstable, prone to violence and easy targets of foreign intervention and control. Left unchecked, Iraq will remain hostage to the turbulent region in which it finds itself — and to the price of oil.

This is Iraq’s legacy, but it need not be its destiny. Iraq must reimagine the Middle East, creating new economic, security and political structures that weave Middle Eastern countries closer together while peacefully accommodating the region’s ethnic and religious diversity. In the American-Iranian cold war, Iraq must resist being dragged into a confrontation. We have real interests on both sides and can play an important role in mediating and even defusing that conflict.

In the regional struggle between Saudi Arabia and Iran, Iraq must stand on the side of justice and equity by pushing for free and fair elections, representative government, minority rights and the rule of law in places like Bahrain, Syria, Lebanon and Yemen. Iraq should welcome Turkey’s return to the Middle East, not as a neo-Ottoman Empire but as a successful example of a dynamic economy rooted in a democratic state that respects its Islamic heritage.

And it could halt the drift of the K.R.G. toward independence by creating open and fair Iraqi national institutions and civic culture. These are the best guarantors of national unity.

Finally, to prevent a sectarian war in the Middle East, Iraq must resist the rhetoric of extremists and push for an inclusive understanding of Islam that undermines the viciousness of hateful ideologues.

The passivity and indifference of Iraq’s leaders to these fundamental challenges contrasts with the ferocity with which they have fought their battles for political power and influence, and the frenzy with which they have sought material gain for themselves and their cronies.

Wise leadership and statesmanship could lead us out of this morass. Failing that, the forces buffeting Iraq and the region may very well lead us to a catastrophe.

Ali A. Allawi served as Iraq’s minister of trade, defense and finance in succession between 2003 and 2006. He is the author of “The Occupation of Iraq: Winning the War, Losing the Peace.”

        – New York Times