Theremin‘s device was used by the Soviet Union to spy on the United States. The device was embedded in a carved wooden plaque of the Great Seal of the United States. On August 4, 1945, a delegation from the Young Pioneer organization of the Soviet Union presented the bugged carving to U.S. Ambassador W. Averell Harriman, as a „gesture of friendship“ to the USSR‘s World War II ally. It hung in the ambassador‘s Moscow residential study until it was exposed in 1952 during the tenure of Ambassador George F. Kennan. The existence of the bug was accidentally discovered by a British radio operator who overheard American conversations on an open radio channel as the Russians were beaming radio waves at the ambassador‘s office.