[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2009/images/06/09/art.mullengates0609.gi.jpg caption="Defense Secretary Gates and Admiral Mike Mullen testified on Capitol Hill Tuesday."]
WASHINGTON (CNN) – The U.S. military has between 12 and 18 months to show whether the war in Afghanistan will be a success, and it may have to be done with fewer troops than in Iraq, according to the top men at the Pentagon.
Admiral Mike Mullen, the Chairman of the Joint Chiefs of Staff, said at a Senate Appropriations Committee hearing Tuesday, he does not underestimate the challenge in Afghanistan, but is positive they are moving in the right direction in defeating the Taliban and insurgent forces.
"We've got to reverse of trend of violence over the next 12 to 18 months, and I think it's possible," Mullen said.
"We have the strategy right, we're resourcing it right," he said.
Defense Secretary Robert Gates spoke alongside Mullen at the hearing and warned the conflict would not be over in 18 months, but hoped to at least see a shift in the momentum.
"I think what we are saying simply is that we think that the strategy needs to show some signs that it's working," Gates said, aware of the possibility of American citizens losing favor for the war.
"It's very important for us to be able to show the American people that we are moving forward by the end of the year or a year from now…I think the American people will be willing to sustain this endeavor if they believe it's not just a stalemate," he said.
By the end of this year some 68,000 U.S. troops, about half the level in Iraq, will be in Afghanistan, up from the 58,000 there now.
The additional troops were added at the request of commanders on the ground and approval from President Obama.
Gates expressed reservations about adding additional troops to the fight, and said Tuesday he knows all too well the lessons learned by the Soviets in Afghanistan fighting with more than 100,000 troops in the 1980s.
"If you don't have the right strategy and if you don't have the Afghan people on your side, you will not win in Afghanistan," Gates said.