2. But al-Awlaki was no ordinary enemy. He was a U.S. citizen. By what right does the president order the killing by drone of an American? Where’s the due process?
Answer: Once you take up arms against the United States, you become an enemy combatant, thereby forfeiting the privileges of citizenship and the protections of the Constitution, including due process. You retain only the protection of the laws of war — no more and no less than those of your foreign comrades-in-arms.
Lincoln steadfastly refused to recognize the Confederacy as a separate nation. The soldiers that his Union Army confronted at Antietam were American citizens (in rebellion) — killed without due process. Nor did the Americans storming German bunkers at Normandy inquire before firing if there were any German-Americans among them — to be excused for gentler treatment while the other Germans were mowed down.
3. Who has the authority to decide life-and-death targeting?
In war, the ultimate authority is always the commander-in-chief and those in the lawful chain of command to whom he has delegated such authority.