In an appearance on CNN's "State of the Union" program, Gen. Raymond Odierno said while the withdrawal timetable is on schedule, the Pentagon could adjust the pace depending on conditions in the war-torn country.
Crucial to the American withdrawal, he said, is that Iraqi security forces are able to take over military operations.
"The Iraqi security forces have matured significantly. They are continuing to improve in their competency. So that is helping significantly," Odierno said. "Part of the judgment will be how much can they do."
President Barack Obama has said combat troops will leave Iraq by the end of August 2010, instead of the end of 2011, which was the date set under a U.S.-Iraqi security agreement.
Obama has left up to Odierno to decide how best to redeploy troops amid the violence.
"There's some cells out there who are still capable of conducting suicide attacks," Odierno said. "We still have some very serious incidents based on one this week but it's much safer."