Karlin earned a B.A. degree in political science and Jewish studies from Newcomb College at Tulane University in 2001. She then attended Johns Hopkins University's School of Advanced International Studies, completing an M.A. degree in strategic studies, Middle East studies and international economics in 2005 and a Ph.D. in international relations in 2012.[6][7] Her doctoral thesis was entitled Training and equipping is not transforming: An assessment of U.S. programs to build partner militaries.[7][8]
Upon leaving the Obama administration, Karlin returned to her alma mater, Johns Hopkins University's School of Advanced International Studies, to first become the deputy director of the Strategic Studies Department and later its Director until leaving academia for government. During her time at Johns Hopkins University, she also served as an associate professor.[12] Simultaneously, Karlin served as a nonresident senior fellow with the Center for Security, Strategy, and Technology at the Brookings Institution[13]
In 2018, Karlin was on the National Defense Strategy Commission staff, and a member of the congressionally appointed Syria Study Group.[14]
Biden administration
Karlin was on the defense policy team for the Biden-Harris transition.[15]
In January 2021, Karlin was appointed to serve as the Principal Deputy Assistant Secretary of Defense for International Security Affairs. The position did not require Senate confirmation, and she began service on January 20, 2021, immediately after President Biden was inaugurated.[16] As the most senior member of the International Security Affairs Office, Karlin became the Acting Assistant Secretary of Defense for International Security Affairs, leading the department's relations with nearly 150 countries.[17]
In April 2021, the White House announced that President Joe Biden had nominated Karlin as Assistant Secretary of Defense for Strategy, Plans, & Capabilities. Karlin received Senate confirmation on August 9.[18][19] In this role Karlin led development of the 2022 National Defense Strategy, Nuclear Posture Review, and Missile Defense Review—the first integrated strategy review in Department of Defense history.[20][21] In this capacity, she also was responsible for advising the Secretary of Defense and others on the forces, plans, posture, emerging capabilities, and security cooperation activities necessary to implement the National Defense Strategy. As part of this, she manages policy and strategy for the Defense Security Cooperation Agency (DSCA).[22]
In addition to her role in writing and implementing the 2022 National Defense Strategy, Karlin guided the AUKUS agreement between the US, UK, and Australia, which, according to a speech by President Biden, is meant to help in "developing Australia’s conventionally armed nuclear-powered submarine capacity"[23]
Karlin also helped form a new emerging capabilities policy office.[24]
On 11 December 2023, Karlin announced that she would be stepping down from her position as Acting Deputy Under Secretary of Defense for Policy and Assistant Secretary of Defense for Strategy, Plans, and Capabilities, to take up a position in academia.[25] On July 8, 2024, the Brookings Institution announced that Karlin had been appointed a visiting fellow.[26]
Publications
Karlin is the author of two books, Building Militaries in Fragile States: Challenges for the United States, and The Inheritance: America's Military After Two Decades of War.[27]