Rumsfeld told a Pentagon press conference that military commanders in Iraq would manage the redeployments so that "seasoned" troops see through the current spate of uprisings.
The Defense Department is in the midst of rotating reinforcements into Iraq to take over from the battle-hardened troops who have been there for the past year.
"Because we're in the midst of a major troop rotation, we have a planned increase in the number of US troops in the CENTCOM area of responsibility and indeed, in Iraq," he said. Centcom is the abbreviated name of US Central Command whose region includes Iraq and Afghanistan.
"We're taking advantage of that increase, and we will likely be managing the pace of the redeployments to allow those seasoned troops with experience and relationships with the local populations to see the current situation through," Rumsfeld explained.
Rumsfeld said Tuesday there were about 135,000 US troops in Iraq because of the rotations. The figure will fall back to about 115,000 as the planned rotations continue, officials said.
Rumsfeld said then the "excess" number of troops were being used in the operations ordered since insurgents stepped up attacks.