President Obama has named Christine Fox, former director of the department’s Cost Assessment and Program Evaluation (CAPE) office to be Acting Deputy Secretary of Defense. DoD’s current Deputy Secretary of Defense, Ashton Carter, is stepping down tomorrow and Fox will assume the duties on Thursday.

Fox will be the highest-ranking woman that has served in DoD.

According to a DoD press release, by appointing Fox as Acting Deputy Secretary, Hagel will be able to keep his “senior management team in place and continue their critical leadership of the military services and DoD components.”

In announcing the appointment, Secretary of Defense Chuck Hagel called Fox “a brilliant defense thinker and proven manager.” He said Fox will be help him shape defense priorities “because she knows the intricacies of the department budget, programs and global operations better than anyone.”

Fox served as CAPE director from November 2009 until June of this year. She was responsible for analyzing and evaluating plans, programs, and budgets and was a key leader of DoD’s Strategic Choices and Management Review.

After leaving CAPE in June she served as a principal technical advisor to Johns Hopkins Applied Physics Laboratory, where she provided strategic advice and counsel.

Fox has almost 30 years of experience in defense issues. Prior to joining DoD, she was a member of the Advisory Board of the Applied Physics Laboratory at the University of Washington. Fox served as the president of the Center for Naval Analysis (CNA), a Federally Funded Research and Development Center (FFRDC). While at CNA, she also was Vice President and Director of the Operations Evaluation Group, which assisted operational commanders execute their missions. She has also served as a member of the National Aeronautics and Space Administration’s (NASA) Return to Flight Task Group

Under law, Fox can serve as Acting Deputy Secretary up to 210 days before a nomination is submitted. After the president sends a nomination to the Senate, she can serve in an acting capacity until the nomination is approved.