But Bryan Whitman, a senior Pentagon spokesman, said that the decision to keep the 3,500 or so US soldiers at their base in Schweinfurt, Germany, should not be seen as a sign of larger force cuts to come.
"This is a very narrow decision to hold one brigade and to give the commanders on the ground additional time to continue their assessments," Whitman said on Monday.
"Obviously, there's been a degree of political progress that's been made in the last couple of weeks," Whitman added, noting that Iraq's prime minister designate, Nuri al-Maliki, appeared close to naming a cabinet.
The combat brigade had been scheduled this week to start loading its equipment for transport to Iraq, and the soldiers were to arrive in Iraq in June and assume their operational responsibilities in July, officials said.
The United States has about 133,000 troops in Iraq. The decision to hold back this brigade does not immediately cut the US force, but a reduction will come in July if this unit does not arrive to replace another one scheduled to go home at that time.
Officials said the brigade might deploy later than planned or not deploy at all.
Rumsfeld (R) expects Casey to
recommend new troop levels soon
The deployment of another army brigade already designated to be deployed in Iraq in the coming months also could be put on hold pending the larger decision on troop levels, officials said.
Donald Rumsfeld, the US defence secretary, has said the United States should be able to reduce its troop presence in Iraq - there are about 30,000 fewer now than in December - as US-trained Iraqi security forces assume responsibility for more territory.
Rumsfeld said last week he expected recommendations from General George Casey, the most senior US commander in Iraq, on future force levels sometime after Iraq's cabinet is named, a development expected in the coming weeks.
Tony Blair, the British prime minister, said on Monday that Britain expected to make an announcement about cutting the size of its force in Iraq within the next few weeks.
It has about 8,000 troops in Iraq, mainly in the more peaceful south.