In a leaked diplomatic memo, Ambassador Karl Eikenberry, a former US military commander in Afghanistan, expressed doubts about the competence of the government led by President Hamid Karzai.
The classified memo was sent towards the end of a process of deliberation by the Obama administration over how to proceed in Afghanistan.
The White House insists that President Obama has yet to make up his mind on the issue, and he is expected to continue deliberations during a nine-day trip to Asia which starts today.
Officials have hinted that there are proposals on the table calling for deeper US military involvement in Afghanistan to confront a resurgent Taliban and its al-Qaeda allies.
They had said earlier there are four strategy options Mr Obama is considering - there is growing support among some of his top advisors for deploying 30,000 or more additional troops to Afghanistan.
However, President Obama has doubts over the amount of extra troops to send and is also worried about the timeframe of their tours.
