The commander of U.S. forces in Iraq said Sunday that it will be important to not "overreact" to insurgent attacks as Iraqi forces assume security responsibilities.

The final American combat team formally handed over those responsibilities to their Iraqi counterparts in ceremonies Saturday attended by Gen. Ray Odierno.

On ABC's "This Week," Odierno expressed confidence in Iraqis' ability to keep a hand on security, despite political instability and concerns that insurgent groups will now have a better opportunity to reorganize.

"What we can't do is overreact to incidents," Odierno said. "There are going to be incidents that occur here. There is a level of violence and a level of terrorism here that's going to occur."

The general said the peace would be kept through continued development on the economic, diplomatic, military and political fronts.

"It's not only about our commitment; it's about the Iraqis now having the capability to move forward," Odierno said of the U.S. withdrawal. "And what we've seen over the last two years, that their governmental entities have improved significantly, and they are starting to move forward economically."

Odierno said that the 50,000 troop drawdown was on track for Sept. 1 and not dependent on Iraqis' ability to form a government by then.

"Our numbers are linked to the capacity that the Iraqis — of the Iraqi security forces being able to sustain stability. And I think they are moving toward that capacity," he said.

"And I remind everybody that we'll have 50,000 troops on the ground post-1 September, and that is still a very significant presence to continue to assist the Iraqi security forces as we move forward."