It would take "a complete failure" of Iraqi security forces for the US to go back to war there. That's according to the top American commander in Iraq as the final group of U.S. troops prepare to leave the country.

With a major military milestone in sight, General Ray Odierno says in an interview with the CBS that any resumption of combat duties by American forces is unlikely.

General Ray Odierno, US Forces Commander in Iraq, said, "Certainly if they asked us, we'd consider it. That's part of us developing a long-term strategic partnership with them, that includes a security relationship, so we certainly would consider that. But again, they have not asked us, we'll wait to see what happens. I would tell you they're capable of providing their internal security, they're capable of some foundational external capability."

About 50,000 U.S. troops will remain in the country until the end of 2011 to serve as a training and assistance force. That's a dramatic drop from the peak of more than 170,000 during the surge of American forces in 2007.

Any U.S. role in Iraq beyond the end of 2011, will probably involve assisting the Iraqis secure their airspace and borders.

Odierno says Iraq's security forces have matured. They will be ready to shoulder enough of the burden to permit the remaining 50,000 soldiers to go home at the end of next year.

If the Iraqis ask that American troops remain in the country after 2011, U.S. officials will consider it. But that would be a policy decision made by President Barack Obama and his national security advisers.