U.S. Defense Secretary Robert Gates said it was a mistake to set a deadline to end American military action in Afghanistan.

Gates made that statement during an appearance on ABC's "This Week" broadcast on Sunday.

Some liberals are calling for a deadline to withdraw U.S. troops from Afghanistan while President Obama is re-examining U.S. strategy in the nation.
     
Gates said right now he will not deliver a request to the president for additional troops in Afghanistan even though the U.S. and NATO commander in Afghanistan is calling for a surge.

"I think it's important to make sure we're confident that we have the right strategy in place and then we can make the decisions on additional forces," Gates said.

Gates said if Obama were to choose to increase combat forces, they would not be able to mobilize until January.

"The notion of timelines and exit strategies and so on, frankly, I think would all be a strategic mistake. The reality is, failure in Afghanistan would be a huge setback for the United States," Gates added.

He also discussed consequences he foresees in motivating al-Qaeda.

"Taliban and al-Qaeda, as far as they're concerned, defeated one superpower," Gates said. "For them to be seen to defeat a second, I think, would have catastrophic consequences in terms of energizing the extremist movement, al-Qaeda recruitment, operations, fundraising, and so on. I think it would be a huge setback for the United States."

President Obama sent 21,000 additional troops to Afghanistan earlier this year.