Obama: No 'perfect answers' in Afghanistan

The US President Barack Obama has warned that there are no "perfect answers" in Afghanistan, as he conducts a wide range review of strategy in the war-torn country.

After the G20 summit in Pittsburgh, on a day when NATO announced the death of five more US soldiers in Afghanistan, Obama said he understood that Americans and others were becoming discouraged by the war.

"This is not easy, and I would expect that the public would ask some very tough questions," said Obama, whose task in selling the war to Americans has been complicated by the disputed Afghan presidential election.

"That's exactly what I'm doing, is asking some very tough questions, and you know, we're not going to arrive at perfect answers."

Obama repeatedly said the US mission was to disrupt and dismantle the al-Qaeda, in the kind of language, which some observers see as a possible sign of a narrowing of the broad counter-insurgency fight against the Taliban.

Obama's statement on Afghanistan comes as two US soldiers were killed outright and three died later of their injuries in a trio of separate incidents on Thursday.