Thomas Hegghammer, responding to Yemen expert Gregory Johnsen, argues that radical cleric Anwar al-Awlaki is playing a significant, almost irreplaceable operational role in al-Qaeda in the Arabian Peninsula. He then argues that eliminating him by drone strike would be a bad idea:
Chasing Awlaki is the right thing to do -- but how? Much of the current debate about U.S. policy in Yemen revolves around drone strikes, but a Hellfire missile is neither the only nor the best way to remove this threat. The Foreign Operations Unit is very small and probably not gathered in a single physical location. They may well be hiding in populated areas, where the risk of collateral damage in a drone strike is very high. The best way to deal with Awlaki is to seek his arrest through good old-fashioned intelligence work; that is, collecting signals intelligence, planting informants, and mounting small search teams made up of Yemeni special forces. This is how Khalid Sheikh Mohammad was captured in Pakistan in 2003; there is no reason why the same cannot be done with Awlaki in Yemen.
The most effective way to deal with al-Awlaki aside, legally speaking the administration would argue that once al-Awlaki's role in an organization that has declared war against the U.S. is established, they are justified in using lethal force in self-defense. As State Department Legal Adviser Harold Koh put it months ago, "A state that is engaged in an armed conflict or in legitimate self-defense is not required to provide targets with legal process before the state may use lethal force." The two options also aren't mutually exclusive.