Deborah Haynes in Baghdad
Lieutenant-General Ray Odierno, who has completed a 14-month tour of duty, gave his warning as Mahmoud Ahmadinejad, the Iranian President, announced that he would would make an unprecedented official vist to Baghdad next month.
Mr Ahmadinejad, accompanied by a group of ministers, will meet Nouri al-Maliki, the Prime Minister, and Jalal Talabani, the President, during the two-day trip from March 2.
General Odierno welcomed the sharp drop in violence across the country and highlighted progress on the political front but said that he was aware of the challenges that lay ahead. I am proud that we have been able to increase security here and provide a window of opportunity for the Government to act, the second-in-command of US forces said after a ceremony to hand over control to his replacement.
Preparations are under way for long-awaited provincial elections on October 1 after Parliament passed a key piece of legislation on Wednesday after weeks of delays. Iraqi MPs also approved the 2008 budget and an amnesty law that could lead to the release of thousands of Sunni prisoners.
Anxious to retain the security gains made in Baghdad and other former hotspots after months of fighting and grassroots diplomacy, General Odierno cited the influence of Iran as a cause for concern. I think Iran wants a weak Iraq, he said, speaking at a former palace of Saddam Hussein on a US military base on the outskirts of Baghdad. They want a weak government of Iraq. It is probably in their best interests.
The US accuses Iran of funding and equipping Shia militias in Iraq, a claim rejected by Tehran, which has been rekindling its ties with Baghdad since the fall of Saddams regime.
Heralding closer relations between the two neighbours the Iranian President, a vociferous critic of the US, is set to become the first leader of the Islamic Republic since its creation in 1979 to visit Baghdad.
As well as the problem of Iranian-backed Shia militias, General Odierno said that flushing out the remaining al-Qaeda strongholds, largely in northern Iraq, was another challenge that he was handing over to his successor, Lieutenant-General Lloyd Austin III.
The outgoing commander, who headed the unit that helped to find Saddam in December 2003 during a previous Iraq tour, is credited with being one of the brains behind President Bushs decision to send an additional 30,000 troops to Iraq last year to tackle volatile areas in Baghdad and the surrounding provinces.
General David Petraeus, commander of US forces in Iraq, heaped praise on his deputy at the ceremony to mark the transfer of authority for the command of the Multinational Corps Iraq to XVIII Airborne Corps from Corps III. General Petraeus said: His leadership in developing plans for deploying the surge forces have been brilliant. The extra American soldiers, coupled with a ceasefire by the al-Mahdi Army and a decision by many Sunni fighters to side with the Iraqi Government, are seen as key factors in the drop in bombings sectarian killings, which ravaged Iraq in 2006.
Commanders emphasise that the progress is fragile but more than 20,000 US troops are due to pull out of the country by July, bringing the force size down to presurge levels.
Asked about plans for further troop reductions, General Odierno, who has been tipped to be the next Army Vice-Chief of Staff, said that he thought there should be a pause to enable commanders on the ground to assess what is happening. Robert Gates, the US Defence Secretary, has also voiced such an view.
General Petraeus is due to update Congress on Iraq in April.
Decades of turmoil
1980 Iraq invades Iran
1982 Iraq withdraws from all captured Iranian territory and sought a peace. Rejected by Iran because of the Iranian leader Ayatollah Khomeinis desire to overthrow Saddam Hussain
1983 The war sinks into stalemate. Iraq continues to sue for peace. Its reputation has been damaged by use of lethal chemical weapons against troops and civilians
1988 Iran accepts a UNmediated ceasefire. An estimated one million people are believed to have died
1990 Iraq and Iran restore diplomatic relations
2007 About 500,000 Shia pilgrims from Iran travel to Iraq to visit the Imam Hussein and Imam Abbas shrines in Karbala, and the Imam Ali shrine in Najaf
