State Department says what ambassador tells Obama is confidential . Hamid will reportedly take the ambassador 's letter to Obama . Ambassador reportedly warns Obama against sending more troops to Afghanistan . Ambassador has expressed concerns about Karzai government in past .
State Department says what ambassador tells president is confidential . Hamid Karzai aides question U.S. ambassador 's advice to Obama . Ambassador reportedly warns Obama against sending more troops to Afghanistan . Ambassador has expressed concerns about Karzai government in past .