In 1951, a British radio operator was monitoring Russian air force radio traffic, when he suddenly picked up the voice of the British Air Attaché loud and clear, but a survey of the embassy did not reveal any hidden microphones. The bug was finally discovered by the US State Department in 1952, three ambassadors later, during the tenure of Amb. It gave the bug a virtually unlimited life and provided the Soviets with the best possible intelligence. Instead, the device was illuminated by a strong radio signal from the outside, which powered and activated it.

Unknown to the Americans however, the carving contained an HF radio bug of a novel design, in that it didn't have its own power source and was not connected via wires. It hung in the library at the Residency Spaso House. On 4 August 1945, the Vladimir Lenin All-Union Pioneer organization 1 presented a hand-carved replica of the Great Seal of the United States to US Ambassador Averell Harriman, as a gesture of friendship to the USSR's World War II ally. The device was codenamed LOSS by the US and RAINDEER (Ð¡ÐµÐ²ÐµÑ€Ð½Ñ‹Ð¹ Ð¾Ð»ÐµÐ½ÑŒ) by the Soviets. Instead it is acivated by a strong electromagnetic signal from outside. It is called a passive device as it does not have its own power source. 'The Thing, also known as The Great Seal Bug, was a passive covert listening device, developed in the Soviet Union and planted in the study of the US Ambassador in Moscow, hidden inside a wooden carving of the Great Seal of the United States.

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