The US has said its forces have cleared an area in north-west Iraq of insurgents following a week-long operation codenamed Matador.
Many people have fled to the desert as a result of the US campaign
The Americans said they had killed more than 125 rebels for the loss of nine of their own men, with 40 wounded.
The campaign, involving air strikes and at least 1,000 ground troops, took place close to the border with Syria.
Meanwhile, in the capital Baghdad, a senior foreign ministry official has been shot dead outside his home.
The assassination of Jassim al-Muhammadawy, the director-general of administration at the ministry, followed a suicide car bomb attack on a police convoy in the city in which at least four people died.
About 10 others were killed in suicide bombings in the northern cities of Kirkuk and Mosul.
More than 400 people have been killed in militant attacks since Iraq's democratically elected government was announced at the end of April.
Explosions were heard on the Syrian side of the border during Operation Matador.
The Syrians moved up extra troops as a precaution.
Reports from the area said US troops began pulling out almost exactly a week after the campaign began, and that they had dismantled a pontoon bridge they built across the Euphrates during the operation.
The US said the operation had achieved its goals of eliminating insurgents, and denying a sanctuary and a through route for fighters and materials involved in attacks deep inside Iraq.
"During Operation Matador, marines, sailors and soldiers neutralised this sanctuary, killing more than 125 insurgents, wounding many others, and detaining 39 insurgents of intelligence value," the US military said in a statement.
But there were no reports that they had entered Qaim, a town close to the border known for its insurgent activity.
The area concerned is highly tribal and has traditionally been a route for smuggling across the Syrian border.
The Americans said they would continue to monitor the area and would be back.
The BBC's Jim Muir, in Baghdad, says the operation appears to have exacerbated tribal tensions in the area.
About 250 people fled Qaim into the desert as a result of the fighting and are currently receiving assistance from the Iraqi Red Crescent, the AFP news agency reports.
"I left al-Qaim with nothing. My five-year-old son was killed in the clashes," Hassan al-Kubaissi, 34, told the news agency.
The governor of the province was also abducted by gunmen who said they would only free him if the Americans pulled out.
The operation was the largest campaign against insurgents since the US-led assault on Falluja in November.