“President Barack Obama has the authority to use an unmanned drone strike to kill US citizens on American soil, his attorney general has said.”
So you're using that as justification for this: “He can kill anyone of us without due process using the US Military to do so.”
But:
Your justification doesn't say "kill anyone", it doesn't even say "kill any US citizen"; it says "kill US citizens" clearly indicating "some" but not necessarily "any" or "all".
Your justification doesn't say "without due process". It doesn't address the matter at all. It mentions "authority", but for all you know the "authority" is limited by the requirements of due process."
Your justification doesn't say anything about the US military. They aren't the only ones to have drones.