US officials pressured Afghan President Hamid Karzai to remove a former warlord from atop the energy and water ministry a year ago because of corruption and ineffectiveness, and threatened to end aid unless he went.
Mr Karzai rebuffed the request, according to secret diplomatic records, and the minister, privately termed "the worst" by US officials, kept his perch at an agency that controls $2 billion in US and allied projects.
The state department correspondence, written as Mr Karzai was assembling a cabinet shortly after his 2009 re-election, reveals just how little influence US officials have over the Afghan leader on pressing issues such as corruption.
Reining in graft is seen as vital to Afghanistan's long-term stability.
President Barack Obama this month cited an urgent need for political and economic progress even as military successes have blunted the insurgency in some regions.
But US aid to Afghanistan has continued despite the dispute over the former warlord, Ismail Khan, in December 2009.
US ambassador Karl Eikenberry pressured Karzai to remove Mr Khan, a once powerful mujahedeen commander, from the top of the energy and water ministry, according to two state department reports written at the time by US embassy officials in Kabul.
They were disclosed this month by WikiLeaks.
A December 19, 2009, memorandum distributed internally under Eikenberry's name described Khan as "the worst of Karzai's choices" for cabinet members.
"This former warlord is known for his corruption and ineffectiveness at the energy ministry," the memo said.
Even with US threats to withhold aid, Mr Karzai rejected requests to replace Mr Khan. "Our repeated interventions directly with Karzai
Did not overcome Mr Karzai's deeply personal bonds with Mr Khan," one of the reports said.
Mr Khan, during a briefing interview with The Associated Press, did not respond directly to a question asking whether he was profiting personally from the ministry. He denied any widespread problems of corruption or mismanagement.
"No money is missing from the ministry," he said. "All the income goes directly to the bank."
Mr Khan said he was unaware of any complaints against him or the ministry. "If there have been complaints, nobody has come to me to tell me," he said.