United States Defence Secretary Robert Gates has admitted the US government has no idea where Osama Bin Laden is.
In an interview on ABC TV, Mr Gates said it was years since the US had had reliable intelligence on his whereabouts. He added that if they knew where he was, they would go and get him.
President Barack Obama announced on Tuesday that 30,000 more US troops would be sent to Afghanistan, before a withdrawal begins in July 2011.
Republicans have criticised the date as being arbitrary and a possible encouragement for the Taliban.