This crude propaganda cliche doesn't offer anything for the discussion. If you take an emotional snapshot of a complex situation and assume that's the whole truth of a situation you almost always are pretty far from the truth - even if in some subset of reality this snapshot is true.
My right wing uncle with his gun collection is a bigger threat to the American people. Why did those 400 innocent people die?
[0] https://www.nytimes.com/roomfordebate/2016/01/12/reflecting-...
This is a relevant question, but not precise enough. What I would be interested instead, is, what's the total mean and variance of american lifes saved in all those operations? And more importantly, what other hypothetical possible combinations of these variables (civilians killed, combatants killed, unuidentified casualties, mean and variance of americans saved) we could have if different decisions have been made - i.e. what's the whole problem space?
Of course, this data is impossible to get and hard to estimate, but this is much closer to the real dilemma at hand.