Anwar al-Aulaqi, a U.S. citizen who lead Al Qaeda in the Arabian Peninsula, was killed in a U.S. drone strike in Yemen.
He deserves no sympathy. He took up arms against his country and he died in the process.
Nevertheless, though, he was a U.S. citizen, and he was killed in a country where we are not at war. If this becomes a precedent, it would be deeply troubling.