The commanding general of the war in Afghanistan says US victory in the region may not be a "sure thing" after all.

"I don't think there are any sure things in this kind of endeavor," Gen. David Petraeus told ABC's George Stephanopoulos in an interview published Monday morning. "And I wouldn't be honest with you and with the viewers if I didn't convey that."

The war's top commander, who this year took the reins from Gen. Stanley McChrystal, hedged by claiming neither he or any other top general could ever be "confident" in success, but he insisted it's a "reasonable" possibility that should be sought after.

"I think -- no commander ever is going to come out and say, 'I'm confident that we can do this,'" he said. "I think that you say that you assess that this is -- you believe this is, you know, a reasonable prospect and knowing how important it is -- that we have to do everything we can to increase the chances of that prospect."

The American public has grown increasingly weary of the nine-year war as instances of violence and corruption continue to surface, and concerns have risen that the war was a mistake and that the United States is no better off as a result of it.

A Washington Post-ABC News poll released Monday reflected this declining confidence. It also found that the Afghan public increasingly believes US military presence is doing more harm than good, and harbors rising sympathies for the Taliban. More Afghans than one year ago said violence against US and other foreign troops is justified.

Petraeus acknowledged these setbacks but argued the United States ought to try and persuade Afghans otherwise. He also denied rumors that he had considered resigning from the post.

The Obama administration and military leaders this summer begun to back away from the president's promise of withdrawing troops by July 2011. The White House reportedly hopes to set a new NATO deadline of 2014.

Petraeus also insisted that there has been some progress as some regions of the country are more secure today. But what would victory look like?

"It looks like an Afghanistan that can secure and govern itself," the general said in the ABC interview. "And it's one that incrementally demonstrates the ability to do that, not suddenly."