On January 20, 2025, Mallory Stewart resigned as Assistant Secretary for the Bureau of Arms Control, Deterrence, and Stability (ADS) at the U.S. Department of State. She joined ADS in 2022, after serving as a Special Assistant to President Biden and Senior Director for Arms Control, Disarmament, and Nonproliferation at the National Security Council since January 2021. Prior to joining the NSC, she was the Senior Manager for Global Nuclear Security and Nonproliferation at the Center for Global Security and Cooperation in Sandia National Laboratories. From 2015 to 2017, Ms. Stewart was Deputy Assistant Secretary for Emerging Security Challenges and Defense Policy in the Arms Control Bureau. In that role, she oversaw the Office of Emerging Security Challenges and the Office of Chemical and Biological Weapons Affairs. Before that, Ms. Stewart was an attorney adviser in the Department of State’s Office of the Legal Adviser, beginning in 2002. Ms. Stewart has also worked as a Nonresident Fellow at the Stimson Center, an Adjunct Assistant Professor at Georgetown University’s School of Foreign Service, and as an associate at the law firm of Sullivan & Cromwell. She holds an A.B. from Harvard College and a J.D. from Stanford Law School.