How many civilian deaths are "too many"?
That's a long way of saying "it depends." Killing 1 civilian might be too many to kill a foot soldier at a Taliban camp in the tribal region of Pakistan. Ten thousand might be fine if it meant saving Afghanistan from Taliban rule, as long as that as low as coalition forces could keep civilian deaths.
The same thinking could then be applied to our "war or drugs" -- the killing of several thousand innocent Colombians could be easily justified in order to eradicate the cartels, albeit temporarily.
Do you find that a satisfactory trade-off as well?