At least 70 people, including civilians, have been killed in a Nato attack in northern Afghanistan.
The US administration has expressed "great concern" over the civilian casualties in the air strike, which it said targeted Taliban fighters.
Robert Gates, the US defence secretary, said in an interview with Al Jazeera that the high civilian casualty rate is a problem for the allied effort in Afghanistan.
"Civilians casualties are a problem for us and we are doing everything conceivable to try and avoid them," Gates said.
Al Jazeera's Anand Naidoo reports on how civilian deaths could undermine the support for Nato's operations in Afghanistan.
