Elbridge Colby is co-founder and principal of The Marathon Initiative, a  policy initiative focused on developing strategies to prepare the  United States for an era of sustained great power competition. He is the  author of The Strategy of Denial: American Defense in an Age of Great  Power Conflict (Yale University Press), which The Wall Street Journal  selected as one of the top ten books of 2021.  Previously, Colby was from 2018-2019 the Director of the Defense Program  at the Center for a New American Security, where he led the Center’s  work on defense issues.  Before that, he served as the Deputy Assistant Secretary of Defense for  Strategy and Force Development from 2017-2018. In that role, he served  as the lead official in the development and rollout of the Department’s  preeminent strategic planning guidance, the 2018 National Defense  Strategy (NDS). The NDS shifted the Department of Defense’s focus to the  challenges to U.S. military superiority and interests posed by China in  particular followed by Russia, prioritizing restoring the Joint Force’s  warfighting edge against these major power competitors. He also served  as the primary Defense Department representative in the development of  the 2017 National Security Strategy.