US troops in Baghdad (file photo)

The U.S. military is delaying the deployment of 3,500 troops that were due to begin moving toward Iraq in the coming days.

Defense Department spokesman Bryan Whitman says the deployment delay is based on commanders' assessments of the security and political situation in Iraq, and was approved by Defense Secretary Donald Rumsfeld. But the spokesman says it will not immediately result in a reduction in the number of U.S. forces in the country.

"This does not change the number of U.S. forces on the ground today, or in the near term - [there are] about 133,000 on the ground now; there will be 133,000 next week; there will be 133,000 next month," said Bryan Whitman. "This is a very narrow decision, to hold one brigade from deploying, and to give the commanders on the ground additional time to continue their assessments."

Whitman says the troops who were due to be replaced are not scheduled to leave Iraq until July. At that time, there could be a reduction in U.S. troop strength. But the spokesman says, the U.S. commander in Iraq, General George Casey, could delay the departure of other units, if necessary.

"The adjustment to the unit's deployment was made as commanders assess the security situation on the ground in Iraq," he said. "As all of you know, our decisions about troop levels are condition-based. In consultation with the Iraqi government, commanders continue to assess the situation to ensure sufficient force levels to support the Iraqi government."

General Casey has said he might be able to announce a significant reduction in U.S. troop strength in Iraq fairly soon, but he says he wants to wait for the new Iraqi government to take office and establish itself. U.S. officials say political progress, the strength of the insurgency and the development of Iraq's new security forces are the major factors in determining how many U.S. and other coalition troops are needed in the country.

The Pentagon spokesman, Bryan Whitman, says the unit that has been delayed, which is based in Germany, is now awaiting a decision on whether or when it might be sent to Iraq.