After the capitulation of Germany, Steiner was imprisoned and investigated for war crimes. He faced charges at the Nuremberg Trials, but they were dropped and he was released in 1948. In 1953, Steiner was recruited by the U.S. Central Intelligence Agency to found the "Gesellschaft für Wehrkunde" ("Society for Defense Studies"), composed of former German military officers, as a propaganda tool and a military think tank for the rearmament of West Germany.