A Polish-led multinational force has taken over control of part of central Iraq, in a move by the United States to relieve some of the burden on its own troops.
The force will operate in an area south of Baghdad
US marines handed over to the 21-nation force in a ceremony in the ancient city of Babylon, making Poland the third country after the US and UK to accept responsibility as an occupying force.
The 9,000-strong force will operate in an area south of the capital Baghdad which includes the holy city of Najaf, where a car bomb last Friday killed the leading Shia cleric, Ayatollah Muhammad Baqr al-Hakim.
The handover came as a senior US general discussed a possible deployment of Turkish troops in Iraq with the leadership in Ankara.
Ahead of a meeting with the Turkish defence minister and chief of general staff, General James L Jones said any extra help with peacekeeping efforts would be welcomed by the US.
General Jones is expected later in the day to meet General Yasar Buyukanit, whose forces may be chosen for a mission in Iraq, to discuss the location and size of the force.
Correspondents say the issue of sending troops to Iraq is extremely controversial in Turkey, and any deployment would have to be approved by parliament.
'Ready for attack'
Following the recent events in Najaf US troops will stay in the city for at least two more weeks.
The US commander, Lieutenant-General Ricardo Sanchez, said he had "absolute faith and confidence" in the nations taking part in the Polish-led force.
The force includes troops from Latin America, the Far East and Eastern Europe
Speaking in Warsaw, Polish President Aleksander Kwasniewski said that the troops were ready to face attack and take casualties in order to restore stability.
"I hope things go well, but if they don't we will have to show a lot of composure and understand that this is not a vacation in Iraq but a stabilisation mission," he told Polish radio.
Mr Kwasniewski is expected to visit the region before Christmas.
The US chose Poland to lead the sector in recognition of its support during the recent war and Polish experience in peacekeeping missions.
The force includes 2,300 Poles, over 1,000 each from Ukraine, Spain and Italy, and around 900 Thais.
Other nations are playing a smaller part, including Bulgaria, Hungary, El Salvador, Honduras, Dominican Republic, Romania, Mongolia, Latvia, Slovenia, Lithuania, Kazakhstan, the Philippines and Nicaragua.
The force's support staff will include officers from the United States, Denmark, Norway, and the Netherlands.