Assistant Secretary of Defense for Mission Capabilities

The assistant secretary of defense for mission capabilities is a position in the United States Department of Defense responsible for the overall supervision of mission capabilities, prototype testing, and the demonstration of "multi-domain" concepts. The officeholder is the principal advisor to the Under [Secretary of Defense for Research and Engineering|under secretary of defense for research and engineering].
The position was created in 2023, under the leadership of Defense Secretary Lloyd Austin.
In July 2025, President Donald Trump nominated James Caggy to the position.