His fiefdom was the tribal lands of north/eastern Yemen, a large area that is not under the control of the Yemen government. Neither the Yemenite military nor foreigners are allowed/tolerated in this territory. In this respect, it is similar to the lawless frontier provinces in Pakistan where al-Qaeda/Haqqani terrorists plan attacks against international forces in Afghanistan. For many years the higher AQ/HN operatives in Pakistan have been targeted by US drones.
What we have here then is an American-born enemy combatant commander who is not approachable on the ground by police/military assets. The only way to neutralize this deadly threat is via a Hellfire missile fired from a Predator drone. An Executive Order to locate and kill this terrorist renegade was issued by the CIC. This was not a secret document. It was available to all branches of the US government, all legal entities public and private, and the American public. His violent death should come as a surprise to no one. The writing was on the proverbial wall.