United States Assistant Secretary of Defense

Assistant Secretary of Defense is a title used for many high-level executive positions in the Office of the Secretary of Defense within the U.S. Department of Defense. The Assistant Secretary of Defense title is junior to Under Secretary of Defense. Reorganization Plan No. 6 of 30 June 1953 increased the number of assistant secretaries. The National Defense Authorization Act for Fiscal Year 2023 added three new Assistant Secretary positions under the Under Secretary for Research and Engineering. The list of Assistant Secretaries of Defense includes:

• Office of the Under Secretary of Defense for Personnel and Readiness
  1. Assistant Secretary of Defense for Health Affairs
  2. Assistant Secretary of Defense for Manpower and Reserve Affairs
  3. Assistant Secretary of Defense for Readiness
• Office of the Under Secretary of Defense for Acquisition and Sustainment
  1. Assistant Secretary of Defense for Acquisition
  2. Assistant Secretary of Defense for Energy, Installations, and Environment
  3. Assistant Secretary of Defense for Sustainment
  4. Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs
  5. Assistant Secretary of Defense for Industrial Base Policy
• Office of the Under Secretary of Defense for Policy
  1. Assistant Secretary of Defense for Homeland Defense and Hemispheric Affairs
  2. Assistant Secretary of Defense for Indo-Pacific Security Affairs
  3. Assistant Secretary of Defense for Cyber Policy
  4. Assistant Secretary of Defense for Special Operations/Low Intensity Conflict & Interdependent Capabilities
  5. Assistant Secretary of Defense for Strategy, Plans, and Capabilities
  6. Assistant Secretary of Defense for International Security Affairs
• Office of the Under Secretary of Defense for Research and Engineering
  1. Assistant Secretary of Defense for Science and Technology
  2. Assistant Secretary of Defense for Critical Technologies
  3. Assistant Secretary of Defense for Mission Capabilities.
• Reports to the Secretary of Defense
  1. Assistant Secretary of Defense for Legislative Affairs

Former Assistant Secretary of Defense positions include:

• Assistant Secretary of Defense for Public Affairs, originally established as the Assistant to the Secretary (Director, Office of Public Information) by Secretary James V. Forrestal in July 1948.
• Assistant Secretary of Defense for Networks & Information Integration
• Assistant Secretary of Defense for Internal Communications
• Assistant Secretary of Defense for Global Strategic Affairs