The new US commander in Afghanistan said he sees "areas of progress" in the war but meeting president Barack Obama's goal of beginning a pullout of US troops in July 2011 will depend on conditions at the time.
Army General David Petraeus said in an interview aired on Sunday on NBC's Meet the Press programme that the battle against the Taliban insurgency was an "up and down process" and it was premature to access its success.
"What we have are areas of progress. We've got to link those together, extend them," Petraeus said in an interview aimed at boosting flagging public confidence in the war effort.
He said he would give his "best professional military advice" to Obama about the pullout next year and leave the politics of the war to the president, who will be up for re-election in 2012.
Obama, who has boosted US troop levels in Afghanistan, plans a strategy review in December after the elections. While Congress supported his plan to bolster troop levels, polls show the public remains uncertain about the effort.
Military commanders have warned the battle will only get tougher this year as troops push ahead with plans to take control of Taliban strongholds in the south and confront other insurgents.
"It would be premature to have any kind of assessment at this juncture about what we may or may not be able to transition," Petraeus said.
"He expressed very clearly that what he wants from me is my best professional advice," he said of Obama.
Petraeus said progress began in the spring but there was a long way to go.
"We're here so that Afghanistan does not once again become a sanctuary for transnational extremists the way it was when al-Qaeda planned the 911 attacks in the Kandahar area," he said, referring to the 2001 attacks on New York City and Washington.
