Derek Chollet is an American foreign policy advisor and author currently serving as the Counselor of the United States Department of State. Previously, Chollet was the Executive Vice President for security and defense policy at the German Marshall Fund of the United States. From 2012 to 2015, Chollet was the Assistant Secretary of Defense for International Security Affairs, where he managed U.S. defense policy involving Europe, NATO, the Middle East, Africa, and the Western Hemisphere for Secretaries Leon Panetta and Chuck Hagel. From Wikipedia
