The Army chief of staff, Gen. Peter J. Schoomaker, cautioned that people not read too much into the planning, because it is easier to pull back forces than to get units prepared and deployed at the last minute.
"This is not a prediction that things are going poorly or better," Schoomaker told reporters. "It's just that I have to have enough ammo in the magazine that I can continue to shoot as long as they want us to shoot."
His comments come less than four weeks before congressional elections, in which the unpopular war in Iraq and the Bush administration's policies there are a major campaign issue.
Last month, the top U.S. commander in the Middle East, Gen. John Abizaid, said the military would likely maintain or possibly even increase the current force levels through next spring. There are 141,000 troops in Iraq, including about 120,000 Army soldiers.
In recent months the Army has shown signs of strain, as Pentagon officials have had to extend the Iraq deployments of two brigades in order to bolster security in Baghdad and allow units heading into the country to have at least one year at home before redeploying.