Ross Douthat has a very smart and thoughtful post. His conclusion:
If you find yourself saying that a modern state cannot take the fight to a terrorist regime if doing so unavoidably involves civilian casualties, you're advancing a theory of jus in bello that no state can accept - and ultimately, I suspect, you're giving ammunition to the side of the debate that wants to do away with moral restraint in the struggle against terrorism entirely.
--Jonathan Chait