The deep divisions over the invasion of Iraq remain. But as our troops return over the next four months, I hope we can begin to be as united about how we support Iraq’s future as we were divided about its past.

I hope we can agree that, whether for or against the war, we have a duty as well as an interest in helping Iraqis rebuild their lives.

A year ago, Iraqis’ number one concern was their physical safety. There are still some bent on violence, but the security situation is now fundamentally different. People’s concerns have shifted towards jobs and electricity. Progress has been driven by a number of factors: the efforts of UK and US troops, including the US surge; the huge improvement in the capability of Iraqi forces; the Sunni tribal awakening against al-Qaeda; and the cessation of Shia militia violence.

Iraq now has a decent shot at making an extraordinary transition: from regional pariah under Saddam Hussein’s brutal dictatorship to regional player within a decade. It is one of the few Middle Eastern states to make a serious, if as yet incomplete, attempt to create a federal political structure that accommodates ethnic and religious minorities. It still has some important nation-building legislation to work through, and the debate about the appropriate balance between the centre and regions has yet to be settled. But the opportunities are real.

First, after decades of repression and years of conflict and violence, “the wheel of democracy”, as Prime Minister Maliki said to me recently, “has started rolling”. More than half Iraq’s population voted in January’s provincial elections. The Sunni communities which boycotted the 2005 elections participated this time. Each of the 14 regional councils was voted out of office; the incumbents accepted defeat, and although coalitions are still being formed, the transition of power is being conducted peacefully.

Iraq’s democratic institutions are still bedding down. Political compromise is still painfully slow. But in the past year the Iraqi parliament has agreed important new laws on investment, detainees and the powers of provincial government. And the country is freer now than in living memory – as a man I met on the Basra Corniche put it, “Life is better than under Saddam: now I can talk.”

Second, although religious tensions remain and the scars of the conflict are still raw, there is reason to hope that, as the first majority Shia democracy in the Arab world, Iraq will play a bridging role between Shia and Sunni poles in the Middle East. And as an exponent of the Shia tradition of Najaf, Iraq offers a democratic alternative to the radical Shiaism being expounded by some in Iran.

Iraqis also make compelling first witnesses for the prosecution case against al-Qaeda across the Muslim world. When the 2006 al-Qaeda attack on the Golden Mosque in Samarra, a sacred shrine for Shias, sparked a wave of Sunni-Shia violence, many warned that Iraq would fracture along religious and sectarian lines. But Iraqis have seen at first hand the vicious hatred and mindless killing that al-Qaeda offers, and they have rejected it in revulsion.

Third, despite decades of economic mismanagement and the destruction of the past few years, Iraq, with the world’s third-largest oil reserves, is set to become a relatively wealthy country.

The short-term problems are real: with oil revenues accounting for 86 per cent of the government budget, the collapse in oil prices means that the Iraqi government will struggle to meet its development and reconstruction commitments this year. But the longer-term outlook is more positive. With improvements in the security situation, many more international companies are looking to invest in Iraq – and with their money will come scientific and technological expertise that the country desperately needs, particularly in
the energy sector. In time, Iraq will be able to use its energy resources to deliver effective public services for its own people and to enhance the energy security of others. Much of its oil will pass through the Strait of Hormuz, but in future some will go north into the European market, enhancing our energy security and diversity of supply.

Last year, General David Petraeus described Iraq’s progress as “fragile and reversible”. It remains so. If we want a secure and prosperous Iraq our engagement cannot end when our combat troops withdraw. As Gordon Brown has said, our future relationship will be one of partnership. We will continue to provide specialist military training to help the Iraqi armed forces provide security. We will step up our support in the education sector and on trade promotion because both are critical to Iraq’s economic prosperity. And we will maintain both a substantive embassy in Baghdad and our missions in Basra and Erbil, because this is a country that is critical not only to regional stability, but also to our counterterrorism agenda and our own energy security.

As Iraq looks ahead, the international community is putting aside the divisions of the past and helping it to build a stable and prosperous nation. President Sarkozy of France, Foreign Minister Steinmeier of Germany and the UN secretary general, Ban Ki-moon, all visited Iraq in February. The lessons of the past will need to be learned. An inquiry will begin after our troops have come home but, for Iraqis, it is also important that we focus on the future.

David Miliband is Foreign Secretary