How the Cold War Began

On September 5, 1945, Soviet cipher clerk Igor Gouzenko severed ties with his embassy in Ottawa, Canada, reporting allegations to authorities of a Soviet espionage network in North America. His defection , the first following the end of WWII, occurring less than a month after atomic bombs exploded over Japan , sent shockwaves through Washington, London, and Ottawa. The three allies, who until weeks earlier had been aligned with the Soviets, feared that key atomic secrets had been given to Russia