You say using drones in a war zone to kill the enemy is legal? Please tell us where this war zone is, and what the bounderies are. It seems your liberal logic is saying it's OK to fire a missile anywhere in the world as long as it is pointed at our enemy (and anyone nearby), but it's NOT OK to capture them (in a country we are not at war with) and flick their ear for a few hours until they give us information on their future plans to kill us. There's something wrong with you and your logic!
PS. as far as killing an American citizen with a drone attack. You might want to read the Eighth and fourteenth Amendments to the US Constitution. It seems Obama has ignored the Constitution AGAIN.