Elbridge A. Colby serves as the Under Secretary of Defense for Policy. In this role, he is the principal advisor to the Secretary of Defense on matters of defense and foreign policy. His duties include leading the development and overseeing implementation of the National Defense Strategy. He is responsible as well for a number of associated strategies and reviews focused on the planning, posture, and management of the Joint Force. Colby also represents the Department of Defense in the interagency and to foreign governments.

Prior to assuming his role, Colby was cofounder of The Marathon Initiative, a think tank focused on preparing the United States for an era of sustained great power competition. During this time, Colby was one of the leading voices for a more realistic and common-sense approach to U.S. foreign and defense policy. His articles and interviews have appeared widely in many of the world’s most prominent outlets, and Colby has also appeared frequently on television and in other media, both at home and abroad. Colby is the author of The Strategy of Denial: American Defense in an Age of Great Power Conflict (Yale University Press, 2021), which was named by The Wall Street Journal as one of the top ten books of that year and has been translated into several foreign languages.

During President Trump’s first term, Colby served as the Deputy Assistant Secretary of Defense for Strategy and Force Development from 2017 to 2018. In that role, he led the development and rollout of the Administration’s 2018 National Defense Strategy, which reoriented the Department to prioritize the threat posed by China’s historic military buildup and emphasized the urgent need for greater allied burden-sharing. Colby also served as the Department of Defense’s primary representative for the development of the 2017 National Security Strategy. 

Earlier in his career, Colby served in a variety of U.S. Government roles working on national security, defense, and foreign policy issues, including with the State Department in Iraq. Colby has also served on the staff of several government commissions and held a variety of roles at think tanks. 

Colby is a recipient of the Distinguished and Exceptional Public Service Medals from the Department of Defense and of the Superior and Meritorious Honor Awards from the Department of State. A member of the Council on Foreign Relations, Colby is a graduate of Harvard College and Yale Law School.