The United States waged a secret propaganda campaign in Japan through films, radio programs and intellectuals during the 1950s in an effort to keep the nation from leaving the Western bloc, a recently found report shows.

The "Report on USIS-Japan," written by Mark May, then chairman of a U.S. advisory group on information, said the objective was "to achieve Japanese identification with U.S. policies."

The United States Information Service was an overseas operational institution meant to influence foreign citizens in promoting U.S. national interests. May, a Yale University professor and expert on psychological warfare, visited Japan for five weeks from June to July 1959 and wrote the report after interviewing various USIS and U.S. Embassy officials.

In the confidential report, he revealed that about half of the USIS programs in Japan were not attributed to U.S. sources. Out of 50 USIS programs "to keep Japan aligned with the Free World and cooperating closely with the U.S.," 23 were not attributed.