DAVID PRATT It was a little over two years ago this month that I found myself in Baghdad's Mansour district accompanying American soldiers during house-to-house searches looking for Iraqi insurgents and arms caches.

"Do not get complacent today, tomorrow or the next day," I remember First Sergeant Brian Fischer, from Texas, telling his men in a pre-operation briefing that morning. "The heat is up and while we ain't going to pick a fight, there's sure going to be one."

Mansour was once uptown Baghdad, an area full of quaint pastry shops and the city's elite living in grand villas. But by then, as in other Baghdad neighbourhoods, insurgents had established a grip on the area and the time had come to root them out.

Under the command of General David Petraeus, US forces had begun what became known as the "surge". The 3rd Stryker Brigade Combat Team, with whom I spent those tense weeks, was part of the spearhead aimed at curbing the insurgency and creating the conditions that would improve security and help reconcile Iraq's warring sectarian factions.

Looking back now to that June day in 2007, and the dangers of rooftop snipers and roadside bombs faced by those US soldiers, they would have laughed in my face had I suggested that barely two years later their comrades would be withdrawing from Iraq's towns and cities.

Indeed, at the time, many in the Pentagon were sceptical of Petraeus's methods. With his penchant for press-up contests and possession of a PhD in international relations from Princeton, he was seen by many as too unorthodox, and unlikely to pull the tactical rabbit out of the hat that would allow a US exit strategy from the military and political quagmire Iraq had become.

This week, though, many of those same sceptics were forced to eat their words, as US troops packed their kit bags and handed over responsibility to Iraqi forces.

But just where does Iraq go from here? Moreover, should the country's future prove to be fairly positive, can we expect a chorus of vindication from certain political quarters over the decision to go to war there in the first place?

In pondering these questions, let us consider one simple fact. Last month alone, 447 Iraqi civilians were killed in continuing violence. This toll was fuelled by several huge bombings - including the deadliest blast this year, in a Shi'ite town near Kirkuk in northern Iraq, where at least 82 people were killed.

Most of these attacks targeted public areas with the aim of killing as many people as possible. Nobody claimed responsibility, but car bombings and suicide attacks bear the signature of al Qaeda in Iraq and other Sunni insurgent groups.

As in the past, their aim remains the same: to foment sectarian violence between Shi'ite and Sunni on a scale comparable to that which almost plunged Iraq into full civil war in 2007.

Having failed to deliver any mortal blow to coalition forces and an ever-stronger Iraqi National Army, the insurgents' strategy in the months ahead will doubtless be much more of the same - igniting sectarian strife.

Should Iraqi forces fail to confront and neutralise the threat, pressure will grow that could result in widespread return of Shia militias, the worst-case scenario being a descent into full-blown civil war.

"Iraqi citizens have been burned by sectarian fire," warned writer and poilitical analyst Abdulmunam al Asam recently. "They fear sectarianism will return, especially after the atrocities that were committed under its name."

Of course, should such a doomsday scenario unfold, many American troops will still be on hand, poised to bail out a beleaguered Iraqi army. The thought of such a reversal must be cause for sleepless nights in Washington.

In many respects, of course, this week's withdrawal is somewhat illusory, with the real test coming after next January's general elections when the Americans start heading home in numbers.

For the moment, though, Prime Minister Nouri al Maliki has sought to capitalise on the recent security gains. And in such a climate it is vital that the Shi'ite-led government take advantage of this new-found hope by pushing forward with political reforms.

It must endeavour to bring together Iraq's factions and encourage greater numbers of Sunnis into the process of governance. Perhaps most urgent of all is the question of how to accommodate the Sunni militias now known as Awakening Councils or Sons of Iraq, who used to be part of the insurgency.

Then there is the pressing question of economic improvement in the lives of ordinary Iraqis, without which the schisms that lie beneath the surface of society will be exacerbated.

Perhaps a lasting peace is really now no longer a pipe dream. Should that be so, doubtless there will be those once again keen to justify the war with echoes of "we told you so". How wrong and misguided that would be. Above all, what Iraq needs now is continuing support of the right kind.

Two years ago in Baghdad, in very different circumstances, I listened to Brian Fischer tell his men: "Do not get complacent today, tomorrow or the next day."

The international community would do well to heed the same message.