US Defence Secretary Donald Rumsfeld has said the number of US troops deployed in Iraq has been increased to 150,000 ahead of next month's scheduled national elections.
He made the announcement in the city of Tikrit, as part of his surpise visit to Iraq on Christas Eve.
The visit followed criticism of Mr Rumsfeld's failure to show sufficient concern for the welfare of US soldiers in Iraq.
Mr Rumsfeld said the trip had been planned for some time to thank troops and wish them a Merry Christmas.
He also visited Fallujah and a US military hospital where some of the survivors of a suicide bomb attack earlier this week in Mosul are being treated.
22 people, including 18 Americans, were killed in the attack.
The US military believes the blast was caused by a bomber wearing an Iraqi military uniform.
