General David Petraeus clapped Sheik Abdul-Sattar al-Rishawi on the shoulder and talked enthusiastically about their new project. "It's men like this who are going to make Iraq work," he said, looking back towards my camera with the confidence of a king.
It was March last year. By September Rishawi, instigator of the "Anbar Awakening", was dead. What he had given to the Americans, however, was the vital Sunni co-operation that had been missing until then from their "surge" plans.
When President Bush adopted the "surge" strategy and appointed Petraeus as overall commander in Iraq, all that seemed important was to increase the number of US troops. Yet four things made up the "surge". Two were within US control - more troops, and more trained Iraqis in uniform deployed with those forces. The other two were less certain - Sunni co-operation in confronting al-Qaeda and Shia co-operation in not attacking everyone else.
After four years of fighting the US occupation, Sunni tribal leaders decided to change sides because al-Qaeda was imposing a harsher Islamic regime than they were prepared to stomach. They formed the "Awakening Councils" and signed 80,000 of their kinsmen on to the Pentagon's payroll to fight beside the US military. The Sunni fighters, together with an increase in Iraqi forces of around 110,000 over the past year, have helped to stem the violence and bloodshed.
Certainly the changes in the Baghdad neighbourhoods I visited while embedded with the US military in early 2007 were secured by enlisting local Sunnis into a home guard. Initially unarmed, these home guards were being trained by US marines by the end of last year. While the US geared up Sunni militias, Shia fighters sat tight. It could have been a recipe for civil war.
"[The] ceasefire has been helpful in reducing violence and has led to improved security in Iraq," noted Rear Admiral Greg Smith, a US spokesman, acknowledging that the success of the "surge" was down to its fourth and least certain constituent - the Mahdi army ceasefire declared by the anti-American Shia cleric Moqtada al-Sadr last August. To the relief of the US military, the ceasefire, which had reversed the statistics of violence, was renewed last month.
Five years after the overthrow of Saddam Hussein, the issue is no longer the chaos unleashed by occupation, but the impact of the expected US withdrawal, both within Iraq and across the region. The UN Chapter 7 resolution that the US quotes as legitimising its 2003 invasion runs out at the end of June. By then, what remains of the coalition will have to negotiate a deal with a weak, fractured government. The Iraqis have to decide on the number of foreign troops they wish to remain in the country, and for how long.
Aware of the potential for renewed civil war as troop numbers fall, both the US defence secretary, Robert Gates, and Petraeus have talked of a "brief period of consolidation and evaluation". This means that as the US presidential race plays out through the summer and autumn, the commanders will take the opportunity to exercise "strategic patience". There will be a halt in troop repatriation, and gains made with the surge will be consolidated. By the time a new president has finally to grasp the nettle, the military and political balance may have stabilised, reducing the likelihood of Washington's greatest enemy, Iran, stepping into a vacuum of withdrawal.
The largely Shia government of Iraq talks to Iranian officials all the time; President Mahmoud Ahmadinejad has just held historic, high-profile meetings in Baghdad. But a fourth round of talks between US and Iranian diplomats, due to be held in Baghdad, should have taken place on 5 March. They didn't happen, for reasons unrelated to Iraq. Because of American efforts to isolate Iran, the US embassy in Baghdad declared there had been no such arrangement.
Iran's influence in Iraq is most visible in the south of the country, where it permeates nearly every faction of Shia politics. A power-sharing agreement is being hammered out by Abdel Aziz al-Hakim of the Islamic Supreme Council of Iraq. The initial part of that understanding was the al-Zahra Charter, which attempted to disarm the Shia militias, leaving use of force solely in the hands of the government. Iran has pushed hard for this, in an attempt to keep the Iraqi government beholden to the Islamic Republic.
Between the overt influence of Shia Iran and the depredations of fundamentalist groups such as al-Qaeda in Iraq, it is no wo nder Rishawi and other Sunni tribal leaders turned to the Americans. They realised they had to get what weapons and backing they could while it was possible. Only thus would they be in a position to defend themselves against Shia militias, the largely Shia government and its Iranian backers when the Americans withdrew.
There is also the fear that the US withdrawal could provoke Sunni nations bordering Iraq to support their fellow believers in a nasty war by proxy. Such a possibility, reinforced by the US's "isolate Iran" diplomacy, makes regional leaders nervous.
In a demonstration of how keen it is to isolate Iran, the US has been arming its authoritarian Arab allies in parallel with Israel. Israel is to receive military aid of £15bn a year over the next ten years, up 25 per cent from present levels. Egypt will receive £6.5bn, while the Saudis will get an arms package of satellite-guided weaponry and other hi-tech munitions worth £10.2bn.
When Bush visited the region in January he repeated often and publicly his theme that Sunni Arabs had to face down Iran "before it's too late". The cautious Saudi foreign minister, Saud al-Faisal, played down the antagonism, insisting that "Iran is a neighbouring country, an important country in the region. Naturally we have nothing bad against Iran."
But he was not being entirely sincere. Reports suggest that Saudi Arabia, along with Egypt and Jordan, could be intending to demonstrate animosity to Iran's friends by sending only officials to this month's Arab League summit in Damascus. Arab leaders are critical of Syrian ties with Iran and Hezbollah, and of their meddling in Lebanon, putting them in what King Abdullah of Jordan has referred to as a new "crescent" of dominant Shia movements or governments - from Iran through Iraq, Syria and into Lebanon. Speaking to the Washington Post in 2004, the king warned: "If Iraq [becomes an] Islamic republic, then, yes, we've opened ourselves to a whole set of new problems that will not be limited to the borders of Iraq."
Maintaining the unity of Iraq has been a core US aim throughout the past five years, but the turbulence of a pullout could, in addition to aggravating antipathy between Sunnis and Shias, result in the Kurdish north declaring independence. After the First World War, the ethnic territory of the Kurds was split by the imperial powers between Syria, Turkey, Iraq and Iran. The consequent struggle for Kurdish independence is closest to fulfilment in northern Iraq. Unsurprisingly, the central government finds itself at odds with Erbil's regional government over who should control local oil revenues.
The issue of independence is focused, in Kurdish eyes, on control of Kirkuk. The decision as to whether Kirkuk remains Arab or becomes Kurdish is due to be made by the end of June; but the issue is so contentious and potentially explosive that it has already been shelved three times since the downfall of Saddam, and will probably be delayed again.
Meanwhile, Turkey fears that independence for Iraqi Kurds would encourage its own Kurdish separatists, the Kurdistan Workers' Party (PKK). In the past few weeks, Turkish forces have entered Iraq to attack PKK fighters operating from the Qandil Mountains. Despite Secretary of State Condoleezza Rice making it clear that "no one should do anything that threatens to destabilise the north", US forces in northern Iraq have, over the past six months, helped to facilitate Turkish military operations at the border.
It is already a year since that hot afternoon when General Petraeus and Sheik al-Rishawi talked of their plans to defeat al-Qaeda in Iraq. The success of the "surge" cannot be denied, but there are long-term implications for the balance of power in the region. The borders that resulted from the Sykes-Picot Agreement of 1916, held so sacrosanct by today's governments and diplomats, may be about to change.
George W Bush and Donald Rumsfeld, the former secretary of defence, planned the war, but not the peace. They should have paid attention to the known unknowns.
Tim Lambon is assistant foreign editor of Channel 4 News