On September 5, 2017, Ryan D. McCarthy was formally sworn in as the Under Secretary of the Army by the Secretary of Defense, Jim Mattis who hosted the ceremony and provided remarks. McCarthy has statutory responsibilities that include 1.4 million Soldiers, Department of the Army Civilians, Reserve affairs, installations, environmental issues, weapons systems and equipment acquisition, communication and financial management, while taking care of Army Families and Soldiers for Life.

McCarthy was unanimously confirmed by the U.S. Senate and appointed as the 33rd under secretary of the Army, Aug. 1, 2017. The under secretary of the Army is the secretary of the Army's senior civilian assistant and principal adviser on matters relating to the management and operation of the Army, which includes development and integration of Army programs and budget. He is responsible for the effective and efficient organization of the Army's operations and initiatives for the business transformation of the Army.