 Following the War, Riley was attached to the staff of Joint Army-Navy Task Force One under Vice admiral William H. P. Blandy as Deputy Air Commander and took part in the Operation Crossroads, nuclear weapon tests at Bikini Atoll in mid-1946.He was subsequently ordered to Washington, D.C., where he joined the Strategic Plans Section in the office of the Chief of Naval Operations under Admiral Louis E. Denfeld.Riley was later appointed an assistant to United States Secretary of Defense James V. Forrestal and following his death in March 1949, he continued as an assistant to his successor Louis A. Johnson.