United States Deputy Secretary of Defense

The United States Deputy Secretary of Defense serves as the principal civilian deputy to the Secretary of Defense within the Department of Defense (DoD). This position is appointed by the President of the United States with the advice and consent of the Senate.

Historical Background

Originally established by Public Law 81-36 on April 2, 1949, the position was initially recognized as the Under Secretary of Defense. It wasn't until Public Law 92-596, on October 27, 1972, that a second Deputy Secretary of Defense position was introduced. The intent was for both deputies to perform duties as prescribed by the Secretary of Defense. However, the second deputy position was filled only once by Robert Ellsworth, who served from December 23, 1975, until January 10, 1977.

Responsibilities and Authority

As the chief management officer of the DoD, the Deputy Secretary of Defense has full power and authority to act on behalf of the Secretary of Defense on any matters authorized by statute or executive order. The Deputy Secretary is responsible for the day-to-day operations of the DoD and assists in the formulation and implementation of national defense policy.

Appointment Criteria

The Deputy Secretary of Defense is required to be a civilian who has been at least seven years removed from service as a commissioned officer on active-duty at the time of appointment. This ensures civilian oversight of the military, a foundational principle in the U.S. defense structure.

Notable Figures

Several individuals have held this significant position, influencing U.S. defense policy through various administrations:

Kathleen Hicks, who served from 2021 to 2025, was notably the first Senate-confirmed woman to do so.
Robert O. Work served under both the Obama and Trump administrations from 2014 to 2017, bringing extensive experience from his prior role as Under Secretary of the Navy.
Steve Feinberg, a former CEO of Cerberus Capital, became the 36th Deputy Secretary in 2025.

Related Positions

The role of the Deputy Secretary of Defense is pivotal in ensuring that the United States maintains a robust and responsive defense posture, capable of adapting to changing global threats and ensuring the security of the nation.