 At Pensacola, Harding was assigned to a seaplane pilot training program. She remained there until 4 August 1920, after which she operated in the Caribbean area tending seaplanes until 23 February 1921. She stopped briefly at Philadelphia before heading to Hampton Roads to support bombing tests on surrendered German ships, leaving Norfolk on 21 June. She was present during the bombing tests on SM U-117 and remained assigned to the tests until the sinking of the German battleship SMS Ostfriesland on 21 July 1921. Harding was detached from this duty the next day.
