Mara Elizabeth Karlin is an American foreign policy and defense advisor. In April 2021, President Joe Biden nominated Karlin to serve as the Assistant Secretary of Defense for Strategy, Plans and Capabilities. She was confirmed by the U.S. Senate by voice vote on August 9, 2021. Previously, she served as the Acting Assistant Secretary of Defense for International Security Affairs. In her role, she served as the main advisor to Secretary of Defense Lloyd Austin on U.S. security policies related to every country in Europe, the Middle East, Africa, Eurasia, and the Western Hemisphere. Her portfolio included shaping U.S. defense policy related to NATO.