Gen. Ray Odierno's comment came on CNN's "State of the Union" when he was asked if unforeseen changes in the Iraqi military or political landscape could prompt U.S. forces to restart combat operations.
"We work very carefully with the Iraqi security forces and we have several different contingency plans for support," Odierno said. "It would have to be something that would change the strategic dynamic here for us to move back to combat operations ... if, for example, you had some political divisions within the security forces that caused them to fracture.
"But," he added, "we don't see that happening. They've been doing so well for so long now that we really believe we're beyond that point."
The last U.S. combat troops pulled out of Iraq last week, ending seven years of combat operations during which more than 4,000 U.S. troops and an undetermined number of Iraqis died. As the combat troops left, a bombing at a military recruitment center in central Baghdad killed more than 50 people.
U.S. President Barack Obama has said the 50,000 U.S. troops staying in Iraq in roles including security and training the nation's security forces will leave by Dec. 31, 2011.
Odierno said the U.S. military is on target to meet that timetable despite persistent violence and political instability in a nation without a government since elections in March.
While conditions in Iraq remain "significantly below" the ""highest levels" the U.S. military hopes to attain, the general pointed to what he called hopeful signs of progress.
"The insurgency is suppressed. There's still terrorism that is occurring here but I will tell you that the country is moving forward," Odierno said.
"It's moving forward along every line. It's moving forward a little bit economically. Its security forces are improving. Its diplomatic efforts are improving. Its governmental functions are improving. So they're headed in the right direction."