The Great Seal bug is found

A carved Great Seal of the United States given to the US ambassador in Moscow in 1945 contained a hidden listening device with no battery. It was found in 1952.

Context

The carving was presented to Ambassador W. Averell Harriman in 1945 as a gesture of friendship from Soviet schoolchildren, the Young Pioneers. It hung in the ambassador's residence in Moscow for about seven years. US staff examined it for wires, but it had none. The room where it hung was used for receptions and meetings.

The device was a passive resonant cavity. It had no battery or power source. A radio beam aimed from outside made it respond, and sound in the room changed its signal, which could be picked up elsewhere. In 1952 a sweep during George Kennan's time as ambassador detected an unexplained signal, and technicians then found the device inside the carving.

The inventor is generally said to be the Soviet engineer Leon Theremin, who also made the electronic instrument that bears his name, and the US code-named the bug The Thing. The Soviet Union was embarrassed when the US raised the matter at the United Nations in 1960. The discovery pushed the US toward more systematic counter-surveillance. The seal was later displayed by the US government as evidence of Soviet eavesdropping, and a replica is often shown in museums.