The American officers gave the wrong coordinates to their Pakistani counterparts as they sought clearance for the air strike that killed 24 friendly troops last weekend, admit officials in both countries.
A senior Pakistani military officer told The Sunday Telegraph that a border co-ordination unit – established to avoid exactly this sort of tragedy – was given incorrect details of a suspected Taliban position.
"The strike had begun before we realised the target was a border post," he said. "The Americans say we gave them clearance but they gave us the wrong information."
The Telegraph also reported that American officers have not disputed the Pakistani account of what went wrong.