Anwar al-Awlaki, a leader of al Qaeda in the Arabian Peninsula, was killed in Yemen today by an American drone strike. He was the first American citizen deliberately targeted and killed by the US government since the attacks of September 11, 2001. Speaking at a retirement ceremony for Admiral Mike Mullen, Chairman of the Joint Chiefs of Staff, President Obama called Awlaki's death a "significant milestone," and "a tribute to our intelligence community and the efforts of Yemen and its security forces, who have worked closely with the United States over the course of several years." Scott Shane is national security reporter for the New York Times.