The below was derived from one in a series of articles ('Classic Quotables') by Don Bishop at the Public Diplomacy Council website, which in turn cited me as the provisioner of the below quote.
The Foreign Broadcast Intelligence Service (FBIS) was established as a subunit under the Federal Communications Commission in March 1941 and operational in June of the same year. The purpose was to monitor broadcasts from around the world and provide valuable intelligence on conditions in other nations. It did not prepare or transmit domestic or international broadcasts. Setup at the suggestion of the State Department, and approved by the Board of War Communications, it operated 'as a central agency serving all Government agencies requiring foreign broadcast material.'
In late 1940, the State Department was concerned about 'anti-American propaganda being short-waved hourly to Latin America' and the Department of Justice was concerned whether 'Axis agents in the United States received direction and guidance from Nazi short-wave programs,' plus a growing concern about 'the growing aggressiveness of Japan as reflected in her radio broadcasts.' Besides knowing what was coming into the United States, the broadcasts were seen as indicators of the thoughts of foreign governments.
This was about the need to monitor the 'new media' for national security.
Leigh's testimony was detailed and delved into Axis and Allied radio activities before and after December 1941. A small example: