Philip Bobbitt has served as a senior adviser at the White House, the Senate and the State Department in both Democratic and Republican administrations, and has held senior posts at the National Security Council, including Director for Intelligence Programs and Senior Director for Strategic Planning. He is currently Professor of Law and Director of the Center for National Security, Columbia University; and Senior Fellow, the Strauss Center for Law and International Security, the University of Texas. He has written books on nuclear strategy, social choice and constitutional law, as well as the celebrated The Shield of Achilles (Allen Lane/Penguin 2002).