Rebecca Zimmerman is the Acting Assistant Secretary of Defense for Homeland Defense and Hemispheric Affairs and is the Principal Deputy Assistant Secretary of Defense for Homeland Defense and Hemispheric Affairs. She is responsible for advising the Secretary of Defense and other senior defense leaders on defense continuity and mission assurance; homeland defense and defense support of civil authorities; Arctic and global resilience; and U.S. defense and security policy for Canada, Mexico, Central America, the Caribbean, and South America.

Ms. Zimmerman previously served as the Deputy Assistant Secretary of Defense for Homeland Defense Integration and Defense Support of Civil Authorities. In this role, she was responsible for developing and overseeing the implementation of policy for the Department’s support to domestic incident response and contributing to the development of homeland defense policy in support of achieving a more secure and resilient nation. Working closely with Federal, State, and local leadership, law enforcement, public health, and emergency management, she oversaw DoD’s response to national emergencies in support of lead federal agencies.

Prior to her appointment, Ms. Zimmerman served as Deputy Assistant Secretary of Defense for Afghanistan, Pakistan, and Central Asia. Ms. Zimmerman spent two decades as a researcher and policy advisor, including at the RAND Corporation, as Editor-in-Chief of War on the Rocks, and in the private sector. Over the course of her career, Ms. Zimmerman has been seconded to multiple deployed operational commands and is an author of numerous studies, including on U.S. military inter-service competition, organizational aspects of competition with China and Russia, soldier attitudes and attrition, and Afghanistan policy.

Ms. Zimmerman holds a B.A. in international relations with honors from Stanford University and an M.A. in strategic studies from the Johns Hopkins University, School of Advanced International Studies.