Foreign forces can't stay in Afghanistan in perpetuity: Obama

US president Barack Obama today said his forces had blunted the momentum of Taliban in Afghanistan and his plans to withdraw American forces next year are on track.

Defending his troop surge strategy, Obama said though the war in Afghanistan remained a difficult task, but their had been a positive trend recently.

Asserting that foreign forces would not be needed "in perpetuity" in Afghanistan, the president in a rare interview to Australian Broadcasting Corporation (ABC) TV recorded in Washington said Karzai was a strong partner with the US in the fight against al-Qaeda.

Obama's comments apparently seek an end a war of words between Kabul and Washington. The president said, "Karzai is capable of leading his country into the 21st century and stabilising it."

"We think it is necessary for the world security that we dismantle al-Qaeda and its affiliate networks, and we need a strong partner in that process."

"I think Karzai has the capacity to be that strong partner and I think we are going to have to...continue to put pressure on him to make the kind of reforms that will not only mean success to us but also ultimately success to him."

Hitting back at criticism that Americans were stalled in Afghanistan Obama said, "I would dispute the notion that it is not getting better. I do think that what we have seen is a blunting of the momentum of the Taliban which had been building up in the year prior to my taking office."

US president made it clear that Washington needed to draw down troops in 2011 and start handing over more responsibility to the Afghans.

In the interview, Obama also said that Washington will maintain efforts to get China, India and other developing countries to make further commitments to fighting global warnings.

He said, he would be visiting Australia in June, a rescheduled visit after he deferred plans to come to Canberra and nearby Indonesia due to last minute lobbying for his health care reforms.