This is the exact moment that sparked the Cold War

On Sept. 5, 1945, a young Soviet cipher clerk in Ottawa, Canada packed his things to leave the office and go home for the day. It was a day like any other day, for the most part, except this time as he put on his coat, he also stuffed a number of top-secret documents underneath. It was just days after the end of World War II in Europe, and the young clerk was hoping these documents would buy him asylum in Canada.

Igor Gouzenko had evidence the Soviet Union was operating an extensive spy operation in Canada. It was the first time the West was forced to come to terms with the idea that the Soviet Union was not their friend.

Igor Gouzenko would appear in television interviews with his identity hidden by a cloth bag.

The documents held by Gouzenko did indeed earn him asylum in Canada. Meanwhile, the Royal Canadian Mounted Police were able to round up 11 of the 24 suspected spies as the Parliament began investigation and prosecution proceedings. Prime Minister Mackenzie King then informed the world about the raids and the spy operation. Gouzenko was subsequently interrogated by MI5, the British internal security service, and the United States Federal Bureau of Investigation, to whom Gouzenko was able to reveal the names of 20 or so spies.

Soviets spies had infiltrated universities, the military, and even the Canadian Parliament, all in search of nuclear secrets. Canada was playing a role in the Manhattan Project, the U.S. development of an atomic weapon, and the Soviets were looking for any clues that would give them an edge in duplicating the effort. The spy ring uncovered by the young cipher clerk extended all the way to Los Angeles.

Gouzenko later wrote a book about the experience.

The documents Gouzenko provided were of so much value, many of them were still classified as of 2014. The young cipher clerk divulged all of the Soviet Union's most sensitive military and intelligence codebooks, and even implicated MI5's former chief Sir Roger Hollis as a Soviet agent. Worldwide, Soviet espionage activities suffered in the immediate aftermath. This was not only due to increased suspicion against their onetime allies and to root out suspected moles but also because the Soviets began to overhaul their own methods.

Soviet installations were suddenly crippled by new safety and reporting procedures, extensive screening processes for overseas stations that were more attractive than the Soviet Union. Even one of Stalin's assassins who was reportedly supposed to kill Gouzenko had been in Canada so long, he didn't want to leave. Rather than kill the traitor, he defected too, giving up information on all of the Soviet death squads in the country.