If we (the USA) were in a declared war or the military action was specifically authorized under the War Powers Act I might agree. But Obama took is into Libya without so much as a nod to Congress and military action over Yemen is murky at best.
I can imagine Obama targeting Americans overseas with a simple after the fact declaration that they were terrorists without any public proof being given. Snuffing American citizens like that without due process or a
recognized State of war is therefore problematic regardless where the action takes place.