Last night, U.S. State Department legal adviser Harold Koh outlined, for the first time, the Obama administration's legal justifications under international law for the targeted killings of non-state actors using remotely piloted aircraft, often referred to as "drones." He inserted the topic of drones into his keynote at the American Society of International Law 104th Annual Meeting at the Ritz-Carlton in Washington, D.C. The United States has used drones since at least 2001 to kill high-level terrorist operatives abroad, particularly in Afghanistan, Pakistan, Somalia, and Yemen. The Obama administration has significantly increased the number of targeted drone killings, according to various non-governmental organizations and media outlets. In this posting, I look at the specific legal reasoning and standards put forth by Koh, the reactions by international law experts, and a few unanswered questions under international law. More