The British government had a well-oiled, coordinated, worldwide strategy during World War II for generating and disseminating rumors, which it called "sibs," short for sibilare, the Latin word for whisper or hiss. Many of the sibs were silly or outlandish—for example, rumors that man-eating sharks from Australia had been deposited in the English Channel to consume downed German aviators—but British intelligence took them extraordinarily seriously.

"The object of propaganda rumours is in no sense to convey the official or semi-official views of H.M.G. [His Majesty's Government] by covert means to officials in the countries concerned,“ read one classified wartime report. “It is rather to induce alarm, despondency and bewilderment among the enemies, and hope and confidence among the friends, to whose ears it comes.”

New sibs were approved by an organization called the Underground Propaganda Committee (UPC), which met weekly in London during the war. While rumors spread in Europe by word of mouth, in the U.S., they were disseminated through a network of friendly reporters and, starting in the spring of 1941, by the Overseas News Agency, a news service that received subsidies from, and was controlled by, the BSC.

ONA articles appeared in newspapers around the country. Especially prior to Pearl Harbor, these stories were picked up by newspapers in Germany, Japan and occupied countries.