Neither bin Laden nor al Awlaki were assassinated. What I meant was that I don't think you think either were assassinated.
As a matter of foreign-policy morality, this goes back to Thomas Aquinas - sometimes you are compelled to do evil in order to prevent a BIGGER evil. Killing a school shooter is evil, for instance, but you are compelled to do so if you can save more lives by killing him. Or a shooter on a bell tower. Or a terrorist.