Episode 39: Cold War Spies and Espionage - I

Igor Gouzenko,  a Soviet cipher clerk stationed at the Soviet Union's Ottawa embassy during the Second World War, defects to the Canadian government with proof that his country had been spying on its wartime allies: Canada, Britain and the United States. This prompts the Gouzenko Affair. His defection is considered the start of the Cold War. In 1946 the United States, working with Britain, deciphers the code Moscow used to send its telegraph cables. As Venona decryption improves in the late 1940s and early 1950s, it blows the cover of several spies, notably the Atomic Bomb spies.