James Risen at the New York Times reports on a concerted campaign by U.S. officials during the Bush Administration to impede the investigation into the mass killings by suffocation and shooting by U.S.-backed warlord forces at Dasht-e-Leili in Afghanistan in November 2001 (emphasis added). American officials had been reluctant to pursue an investigation — sought by officials from the F.B.I., the State Department, the Red Cross and human rights groups …